The Chinese, who have early distinguished themselves in many inventions

that have been worked out and improved upon under our Western

civilisation, introduced piers into their rivers and canals, in order

to overcome the difficulties incidental to falls or shoal water. These

piers have been termed by De la Lande half locks, and it has been

remarked by Chapman that the casual position of two pairs of piers

near to each other has no doubt suggested the invention of locks, as

it would be seen, when the gates of the lower piers were closed, and

of sufficient height, that the water would be nearly still between the

upper pair of piers, and afford an easy passage, so that, in place of

a single pair of piers, two pairs would be erected sufficiently near

to each other for the purpose, and capacious enough to hold a fleet

of boats. It would soon afterwards be found that in dry seasons the

waste of water was greater than could be conveniently afforded, and the

operation was tedious for single boats. Thus would progressively arise

the invention of locks with walled chambers and sluices through their

gates and walls. There are, or were recently, on some rivers, locks of

the first construction, composed simply of two pairs of piers, without

any connection of walls or pavement between them. The Kennet and the

Lea have unwalled locks. Thomas Telford, when projecting the Inverness

and Fort William Canal, on account of the great plenty of water, and

size of the vessels to be used, proposed not to wall the locks the

whole length, but to have earthen banks between the two pair of piers

of masonry that support the upper and lower gates of the locks.

It appears from M. De la Lande’s ‘Traité des canaux de Navigation,’

that the first lock was supposed to be erected in the year 1488, upon

the Brenta, near Padua; and that shortly after, the two canals of

Milan, between which there was a fall of nearly 34 feet were joined by

means of six locks, similar in principle to those at present in use.

The first lock that James Brindley erected appears to have been at

Compton, on the Stafford and Worcester Canal; but they were not at that

time uncommon in England, on several of the rivers, and on the Sankey

Canal.

PLANES.

William Reynolds, of Ketley, in Shropshire was the first who

contrived and executed an inclined plane (which was completed in

1788) for the passage of boats and their cargoes. It was found to

answer the purpose, and continued in practical use. Thomas Telford

has thus described the plane, in ‘Plymley’s Agricultural Report of

Shropshire’ (p. 291): “Mr. Reynolds having occasion to improve the

mode of conveying iron, stone and coals, from the neighbourhood of

the Oaken-gates to the ironworks of Ketley, these materials lying

generally at the distance of about a mile and a half from the

ironworks, and at 73 feet above their level, he made a navigable

canal,” called the Ketley Canal, “and instead of descending in the

usual way, by locks, continued to bring the canal forward to an

abrupt part of the bank, the skirts of which terminated on a level

with the ironworks. At the top of this bank he built a small lock,

and from the bottom of the lock, and down the face of the bank, he

constructed an inclined plane, with a double iron railway. He then

erected an upright frame of timber, in which, across the lock, was

fixed a large wooden barrel; round this barrel a rope was passed

and was fixed to a movable frame; this last frame was formed of a

size sufficient to receive a canal boat. These boats were 20 feet

in length, 6 feet 4 inches wide, 3 feet 10 inches deep, and each

carrying 8 tons, and the bottom upon which the boat rested was

preserved in nearly a horizontal position, by having two large wheels

before and two small ones behind, varying as much in the diameters

as the inclined plane varied from a horizontal plane. This frame was

placed in the lock, the loaded boat was also brought from the upper

canal into the lock, the lock gates were shut, and on the water

being drawn from the lock into a side pond, the boat settled on a

horizontal wooden frame, and as the bottom of the lock was formed

with nearly the same declivity as the inclined plane, upon the

lower gates being opened, the frame with the boat passed down the

iron railway on the inclined plane on to the lower canal, which had

been formed on a level with the Ketley iron works, being a fall of

73 feet. Very little water was required to perform this operation,

because the lock was formed of no greater depth than the upper canal,

except the addition of such a declivity as was sufficient for the

loaded boat to move out of the lock; and in dry seasons, by the

assistance of a small steam engine, the whole of the water drawn off

from the lock was returned into the upper canal by means of a short

pump. A double railway having been laid upon the inclined plane, the

loaded boat in passing down brought up another boat containing a load

nearly equal to one-third of that which passed down. The velocities

of the boats were regulated by a brake acting upon a large wheel

placed upon the axis, on which the ropes connected with the carriage

were coiled. It appears that this plane has an inclination of about

22°, except near the extremities, where it diminishes to about 111°;

and that about 400 tons of coals usually descend thereon daily.” In

1789 a copper medal, or halfpenny, having a representation of this

plane on one side, and of the cast-iron bridge at Coalbrookdale on

the other, was struck and issued by the Coalbrookdale Company. After

the practicability of inclined planes had been established, by the

success of the Ketley plane, few Acts were passed for a new canal,

without a clause authorising the company to erect inclined planes,

instead of locks, if they should be found most advisable.

At Walkden Moor, an underground plane was completed in October 1797,

upon the Bridgwater Canal, similar to the Ketley plane above described.

Reynolds introduced another form of inclined plane on the Shropshire

Canal, where there were three planes employed of 120, 126, and 207

feet rises. The Act for this canal was obtained in 1788, and it

was completed and opened in 1792. These planes were of the same

construction as those at Ketley, except that there were no locks at the

top of the descending planes, but the latter were continued above the

surface of the water in the upper canal and terminated in a cross beam,

from which another plane and railway descended into the upper canal,

this being intended to avoid the waste of water which locks at the top

of the planes occasion.

The first incline up which barges were conveyed in a large caisson

containing water was at Blackhill, on the Monkland Canal, near Glasgow,

the system having been previously introduced, on a small scale, on

the Chard Canal in Somersetshire. The Blackhill incline, with a rise

of 96 feet, and a gradient of 1 in 10, replaced two flights of four

locks each. The wrought-iron caisson, 70 feet long, and 13⅓ feet wide,

runs on twenty wheels, and carries barges of 60 tons on the incline.

An incline with larger caissons was constructed at Georgetown in 1876,

in substitution for two locks connecting the Chesapeake and Ohio Canal

with the Potomac. This incline rises 39 feet, with a gradient of 1 in

12; and barges of 115 tons are transferred from the lower to the upper

reach in 8 or 10 minutes. The caisson is 112 feet long, 16¾ feet wide,

and 7⅚ feet high. It is carried on three trucks, with twelve wheels

each, and is drawn up by wire cables worked by a turbine.

A canal incline, as described by Mr. Vernon-Harcourt,[275] consists of

two lines of way, laid on a steep uniform gradient, on which barges

are drawn up or let down, by wire cables, from one reach to the next,

either resting on a cradle, or water-borne, in a caisson, running

on wheels on the incline. The cables wind round a drum at the top

of the incline; and the ascending barge is generally more or less

counterbalanced by another descending, whereby the tractive force

required to pull the barge up is considerably reduced. Primitive

inclines exist on the Bude Canal in Cornwall. Inclines are often

used, as alternatives to locks, as at Hampton Court, on the Thames.

Inclines, up which barges are drawn in cradles, were carried out on the

most extensive scale on the Morris Canal in America, where there are

twenty-three inclines with gradients of 1 in 10, and an average lift of

58 feet. The largest of these is 1100 feet long, and rises 100 feet;

and barges of 70 tons are drawn up the inclines.

LOCKS.

In the great majority of cases, however, locks are the means adopted

for overcoming differences of level. In Great Britain it is calculated

that on the existing canal system of 2240 miles, there are 1901 locks,

being at the rate of one lock to every 1·37 miles of canal, of which

931, or nearly one-half, are 80 feet long or more.[276] This, of course,

means very slow transport and great loss of time. On the canal system

between Birmingham and London there are about 130 locks in all.

The loss of time due to the passage of locks arises from two causes,

one of which, as Mr. Conder points out,[277] it is easy to calculate,

while the other varies extremely according to the management of the

line, and the nature and volume of the traffic. The rise or fall of the

water in the lock occupies an ascertainable time, ranging from three

to six minutes; but the time lost in entering and leaving the locks

is less easy to calculate. With perfect arrangement the loss is very

small; frequently it is, in fact, very considerable. “In the event of a

heavy traffic being thrown on our canals, it will probably be advisable

to double the locks, a communication being made practicable between

the pair, in order to save half a lock full of water at each passage.

With this arrangement much time as well as much water may be saved.

The average retardation due to the hydraulic requirements alone of

the locks on the English canals is from 1¾ to 2 minutes per mile, the

average rise to be overcome being under 6 feet per mile of canal.”

In France, on all the more important canal routes, the locks are

designed to accommodate the large _péniches_ or boats of 270 tons

burden, 116 feet long, and 16 feet beam, which are the usual craft

employed. In cases of exceptional traffic, the locks are made 130

yards long by 13 yards wide, in order to allow of several vessels

passing through together. These arrangements are very favourable to the

transport of large quantities of freight, so much so, that it is no

unusual thing to see 25 to 30 barges, each laden with 270 tons of coal,

towed by a small tug of 20 horse-power, working a submerged chain or

wire rope, which the tug raises from the bottom as it progresses, the

rope being nipped between revolving pulleys.

The time occupied in passing through a lock on the French canals used

to amount to from 16 to 20 minutes at least. The time is spent in

filling or emptying the lock, in closing and opening the lock-gates,

and in passing the barge into and out of the lock-chamber. The

adjustment of the water-level in the lock-chamber may be hastened

by large sluices in the side walls of the lock. The moving of the

lock-gates can be rapidly effected by hydraulic machinery. Delays have

been experienced in dragging a barge into or out of the lock when it

is nearly the width of the lock-chamber, owing to its acting like a

piston, and preventing the flowing back of the water along the sides;

but this inconvenience can be obviated by carrying the culverts for the

sluiceways all along the side walls, and providing lateral openings

through which the water finds an exit.

The dimensions of the canal locks resolved upon in France, under the

extension scheme of 1878, was 126·2 feet in length by 17 feet in clear

width, and 6·56 feet of water on the sill of the lock-gate. Boats of

120 tons burden can make use of such locks without difficulty. No canal

in England, except the Gloucester and Berkeley, has locks of this size.

The nearest approach to such dimensions is that made by the Grand

Junction Canal, with locks 87 feet 6 inches long, 15 feet in the clear,

and a depth of 5 feet, allowing, however, for the passage of an 80-ton

boat only. The Grand Union Canal, which is connected with the Grand

Junction, has only locks of 78 feet by 7 feet 2 inches. It has been

computed that the difference between the cost of locks for a 120-ton

boat and that of locks suited for an 80-ton boat is not more than

3000_l._ per mile.[278] Assuming the accuracy of this figure, the cost of

enlarging the dimensions of the principal British canals ought not to

be a serious item.

Locks provided with sluiceways running the whole length of the side

walls have been constructed on the Aire and Calder navigation, on the

Scheldt and Meuse Canal, and the Canal du Centre of France. These

large sluiceways ensure the rapid filling or emptying of the lock;

and by making several side openings along the side walls into the

lock-chamber, the inflowing or outflowing currents are distributed so

as to have no injurious effect on the vessel inside.

[Illustration: _DOMINION OF CANADA._

GENERAL PLAN OF ENLARGED LOCK

_ON THE_

_S^T LAWRENCE AND WELLAND CANALS_.]

[Illustration:

_E & F N Spon. London & New York_

“INK-PHOTO” SPRAGUE & CO. LONDON.

VIEW FROM THE NIAGARA ESCARPMENT, LOOKING UP THE WELLAND CANAL TOWARDS

LAKE ERIE.]

Balanced cylindrical sluice-gates, rising and falling vertically in a

circular well communicating with the sluiceways, have been adopted at

the new locks of the Scheldt and Meuse Canal, and the Canal du Centre,

for opening and closing the sluiceways easily and rapidly. The enlarged

locks on the Canal du Centre can be filled or emptied in two minutes;

and the passage of vessels through the locks takes less than half the

original time.

Mr. E. J. Lloyd, speaking from experience of canals in the Midlands, is

of opinion that a multiple of the present size of lock which prevails

throughout the Midland district would be best. This would enable the

existing craft on those canals, and also most of the barges on larger

navigations, to be used in the most economical way possible. It would

greatly simplify the conduct and management of low-class mineral

traffic, which does not require any care, and could be treated in a

similar manner to traffic of the like description on railways—no crews

being attached to the boats, which could be detached from the trains,

and left at any roadside wharf, until they could be unladen at the

convenience of the owners.

There is, no doubt, as Mr. Lloyd points out, a distinct advantage in

small craft for such traffic, as it is obvious that a coal merchant

could purchase small boat-loads of different classes of coals, to suit

his customers, who could not find capital and wharf space for large

cargoes of one class of coal only, and this would apply in equal degree

to traffic in road-stone, bricks, drain-pipes, building materials,

and many other classes of undamageable goods, and these small craft

might also ply successfully on short branch canals, in districts which

would not produce a sufficient traffic to warrant a large expenditure

in improvement. Such locks would also, of course, accommodate craft

sufficiently large to cross the estuaries of rivers, and to approach

any docks with safety, and if sufficient depth of waterway is provided

in the improved main lines, say 8 feet, or thereabouts, short coasting

voyages might also be undertaken by craft specially constructed to do

so, and also to navigate the canals.[279] Mr. Lloyd thinks that the heavy

cost involved in constructing canals of sufficient size to pass craft

suitable for coasting and short continental voyages would be fatal to

cheap conveyance.

The largest locks hitherto constructed are those on the St. Mary’s

Falls Canal, in the United States, and the Welland Canal in Canada.

On the former canal the lock opened in 1851 is 515 feet in length and

80 feet wide. The great tidal lock at Eastham, on the Manchester Ship

Canal, will be 600 feet long and 80 feet wide.

_The Welland Canal_, which is in some respects the most important in

Canada, was begun by a private company in 1824 and opened in 1829. The

original locks were of wood, 110 feet by 22 feet by 8 feet, and they

bulged out on each side of the chamber to such an extent that they had

to be hewn down from time to time to let vessels pass through. The

canal was enlarged in 1841, and again in 1871, the depth of the canal

having, on the occasion of the last enlargement, been increased to 14

feet. The drawing (p. 415) shows the general plan of the enlarged lock

on this canal. It is 270 feet between the gates, 45 feet between the

side walls, and has 12 to 14 feet of water upon the mitre sill.

The entire system of locks on the _Manchester Ship Canal_, now under

construction, will be as under:—

Three locks at Eastham, namely, one 600 feet long by 80

feet wide; one 450 feet long by 50 feet wide; one 150 feet

long by 30 feet wide.

Two locks at Latchford, namely, one 600 feet long by 65

feet wide; one 450 feet long by 45 feet wide.

Two locks at Irlam: similar to Latchford.

Two locks at Barton: similar to Latchford.

Two entrance locks to docks: similar to Latchford.

Small lock (Weston Marsh Lock), 229 feet long by 42 feet

8 inches wide, to connect the ship canal with the Weston

canal.

Weston Mersey Lock, opposite Weston Point; 600 feet long

and 45 feet wide.

Bridgwater Lock, opposite Bridgwater Dock, Runcorn, 300

feet long and 45 feet wide.

Runcorn Old Quay Lock below Old Quay Docks, Runcorn, 300

feet long and 45 feet wide.

The three locks above mentioned connect the ship canal

with the Mersey Estuary at their several points.

Two small barge locks at Walton and Stockton Heath,

Warrington.

[Illustration: MANCHESTER SHIP CANAL

ENTRANCE LOCKS AT EASTHAM.]

The largest canal locks hitherto contemplated are those designed by

Col. Blackman for the proposed _Nicaragua Canal_. They are 700 feet

long, 100 feet wide, and with 30 feet depth of water over the sill;

whilst the lift proposed is from 50 to 120 feet. The filling of the

lock-chamber was to be rapidly effected through 18 feet cast-iron

pipes, built into the side walls along the whole length on each side,

connected across the bottom of the lock-chamber by a series of 3-feet

pipes, perforated by a number of 2-inch holes, from which the water

was to be distributed over the whole area of the chamber in numerous

small streams, so as to avoid any prejudicial agitation of the water.

The emptying was to be similarly effected; and where a saving of water

is important, the pipes were to discharge at the lower end into a

series of long ponds, formed in terraces, so that most of the water

might be used again for filling the lock. These arrangements are a

large extension of the system of sluiceways, all along the side walls,

with lateral openings, and of side ponds, already referred to. The

most novel feature was the form of the caisson-gate, proposed to be

constructed of wrought iron and steel, which, being increased in width

towards the bottom, would become stronger in proportion to the depth,

as the water-pressure increases.

HYDRAULIC LIFTS.

The adoption of hydraulic lifts, in the place of locks and inclines,

has recently come prominently to the front. The first lift of this

description[280] was erected on the Weaver Navigation in 1875, for the

purpose of connecting that river with the Trent and Mersey Canal. In

this case the difference of level between the canal and the river is

rather over 50 feet. Two wrought-iron troughs are employed to raise

and lower the barges. The troughs are 75 feet by 15½ feet, and have 5

feet depth of water. They rest on a central hydraulic ram, three feet

in diameter, working in two hydraulic presses underground, which can be

connected at pleasure, making the troughs counterbalance one another.

One trough ascends as the other descends. Hydraulic power is only

required when the descending trough reaches the water in the lift-pit,

the motion of the troughs being effected by removing about six inches

from the lower trough. This arrangement is very economical of time,

inasmuch as a 100-ton barge can be transferred from the river to the

canal, and another from the canal to the river, in eight minutes.

Although the difference of level, as already stated, is 50 feet, only

the final lift of 4½ feet requires the expenditure of hydraulic power.

La Louviére hydraulic lift, which was only completed during the summer

of 1888, is the largest hydraulic canal lift in the world. It was

constructed for the Belgian Government by the Société Cockerill, of

Seraing, from the designs and under the superintendence of Messrs.

Clark, Stanfield and Clark, of Westminster, the consulting engineers of

the Government, and the patentees of the system. The difference between

the levels of the upper and lower canals—that is, the height the boats

are raised—is 50 feet 6¼ inches. The lift consists of two pontoons

or troughs, each 141 feet long by 19 feet broad, with 8 feet draught

of water, and are capable of holding the largest size of barge that

navigates the Belgian broad-gauge canal system. Such barges are capable

of taking 400 tons of coal or other cargo, so that the total weight of

the trough, water, and barge is not much under 1000 tons. This immense

weight is supported on the top of a single colossal hydraulic ram of 6

feet 6¾ inches diameter, and 63 feet 9½ inches long, working in a press

of cast iron, hooped continuously for greater security with weldless

steel coils. The working pressure in this press is about 470 lb. to the

square inch. The time actually occupied in the operation of lifting or

lowering is only two and a half minutes. (See illustration at p. 141.)

It is probable that there is a greater liability to accidents, with

lifts than with either locks or inclined planes. Where a dead weight of

some hundreds of tons has to be moved bodily, it must, of course, be

necessary to provide correspondingly strong machinery, and this is not

to be done without considerable cost. Several accidents have, indeed,

recently occurred in hydraulic presses for lifts. One of these occurred

with a steel press which burst under a pressure of 70 atmospheres.

Another happened with a riveted steel-plate press, which leaked and

rent under pressure.

On the Brussels and Charleroi Canal it was recently proposed to apply

an hydraulic lift, for which the Cockerill Company made a cylinder,

in which tightness was obtained by the use of cast iron, and strength

by the use of steel, the cylinder being cut with projecting rings,

turned to receive steel hoops, which were bored to a slightly smaller

diameter, put on hot, and allowed to contract. A cylinder 2·06 metres

(6 feet 9 inches) in diameter and 2 metres (6 feet 7 inches) high, was

subjected, by means of force-pumps, to an internal pressure of 131

atmospheres, or four times that which would be required in practice.

The French engineers, following the Seraing system, formed their

cylinders of a series of steel hoops fitting one into the other, and

with the flanges of the two outside hoops drawn together by tie-rods,

the inside being lined with brass 0·0025 metre thick, applied with the

mallet, so that the water may not come into contact with the joints. A

trial cylinder was tested up to 170 atmospheres without yielding. On

the Brussels and Charleroi Canal, however, it was decided to substitute

a tunnel for the intended lift, so that the Cockerill cylinders were

not applied.

Inclines, or lifts, are said by some authorities to effect a great

economy, both in time and water, as compared with flights of locks.

Much, however, must depend upon local circumstances.

One problem that is likely to press for solution in the immediate

future is that of constructing locks or lifts that will enable ship

canals to be worked with facility and economy. The proposal of the late

Mr. Eads to construct a ship railway across the Isthmus of Tehuantepec

was intended to overcome the necessity of such a canal, and was,

indeed, a form of lift, of the practicability of which, however, we

still await a conclusive demonstration. There is, of course, a natural

limit to the size of locks that it is possible to work. That limit,

however, does not appear to have been reached in any locks hitherto

constructed. The Eastham locks on the Manchester Ship Canal will be

the largest hitherto made; but we have seen that locks, even 100 feet

longer, have been proposed for the Nicaraguan Canal. Of course, by

the application of steam power, canal locks may be made of larger

dimensions, and there are some instances in which such power has been

attended with much advantage.

In 1868, steam-power was applied to the locks of the Delaware and

Raritan Canal, and is said to have increased their capacity for

traffic, and therefore that of the canal, by 50 per cent. The engine

has two cylinders, 6 inches diameter, 12 inches stroke, and works a

3-feet drum, actuating a 1-inch wire rope, which passes over rollers,

along the face of the lock, and round sheaves above and below. To this

rope the boats are attached and hauled in and out, two at a time. The

engine also raises and lowers the valves, opens and shuts the gates,

and in one case works a swing bridge. For large docks (e. g. 600 feet

by 800 feet) it has been proposed[281] to admit and take off the water by

channels the full width of the length of the lock, the water entering

and leaving the lock by a number of small sluiceways, through the

walls at right angles to the axis. This water should, if possible, be

supplied, not from the reach above, but from separate reservoirs. There

will thus be two waterways at right angles to reach each other, one

longitudinal for the passage of vessels only, and one transverse, for

the passage of water only. This avoids the expense of maintaining the

paddles in the lock gates, and all the risks attending longitudinal

currents. The canal should be widened above and below by floating

pontoons, not by fixed walls. The height of the lift may be varied

as required up to 30 feet; a lift of 33 feet has been worked for

twenty-five years with ease and safety.

FOOTNOTES:

[272] These locks will be found described and illustrated in a

previous chapter.

[273] Zendrini’s ‘Della Acque Correnti,’ c. 12.

[274] ‘Encyclopædia of Civil Engineering.’

[275] Report of the Conference on Canals and Inland Navigation, held

at the Hall of the Society of Arts in 1888, p. 5.

[276] Report of the Select Committee on Canals, 1883, p. 125.

[277] Paper on “Inland Transport in the Nineteenth Century by Land

and Water.”

[278] Mr. Conder on ‘Inland Transport in the Nineteenth Century by

Land and by Water.’

[279] Report of the Conference on Canals and Inland Navigation,

‘Journal of the Society of Arts,’ for 1888.

[280] On the Great Western Canal, a simple lift, with two

counterbalancing troughs, was used in the early part of the century,

but it was not found successful.

[281] Min. Proc. I. C. E., vol. lxiii. p. 350.

CHAPTER XXX.

TUNNELS, VIADUCTS, EMBANKMENTS, AND WEIRS.

In the laying out of a canal there generally comes a juncture at which

the engineer has to choose between a tunnel, a flight of locks, a lift,

or series of lifts, and, finally, an embankment. There are also cases,

although these are comparatively rare, in which a valley has been

crossed, and the level of the water maintained, by aqueducts.

Tunnelling is always a costly operation, and it seldom happens that it

gives a considerable advantage, if any, over locks in the matter of

speed. Nevertheless, many of the early canal engineers were partial to

tunnels, and hence there are many examples of such structures on the

canal system of Great Britain. Of some of these we may suitably furnish

particulars before proceeding to refer to more recent works of the same

character.

One of the earliest canal tunnels of which we have any record was

constructed by Brindley on the Bridgwater canal. This tunnel gave

the Duke access from his canal into the coal works at Worsley, and

after it had proceeded for some way straight into the hill, came at

a great depth to be under a small brook or constant stream of water,

by the side of which a large water-shaft was sunk, and a drum and a

large brake-wheel erected over it, of such size that a man who stood

before the lever had his two hands at liberty to pull the lines which

connected the valves, and give signals to those below, while by lunging

or stepping forwards, with his breast against the lever, he could in

an instant stop the machinery in any part of its motion, or regulate

the same at pleasure. There were two water-tubs, which were very large,

and had a valve and pin to empty themselves quickly when they arrived

at the bottom. They were suspended by large ropes or cables from the

drum, while other large ropes descended therefrom through another or

coal-shaft, by the side of the middle or principal tunnel, into and

over the navigable tunnel, which is there at some 60 yards lower level.

On this level, canal boats were used, similar in their dimensions to

those above, and containing boxes, which being filled with coals at the

several terminations of the canal, in the seams of coals, were pushed

along by means of rings fixed along the roof of the tunnel at the

proper height for a man, who walked on the top of the coals, to lay

hold of, and shove the boat along by. The boat having arrived under

the coal shaft, and one of the water-tubs being at the top of its

shaft, the coal rope answering thereto was hooked on to the box of

coals, and the descent of the water-tub, immediately on the ringing of

a bell, drew up the same to the level of the principal canal, where,

being drawn aside over an empty boat, it was lowered into the same by

a slight reversion of the motion of the machine, when the interval

of emptying the tub at the bottom by its valve gave time for hooking

another box to the other rope which was at the bottom, when the other

water-tub was filled, and the machine was suffered to move by the man

who leant against the brake.

This arrangement was contrived and erected by James Brindley, and it

was so constructed that when coals were not drawing, the alternate

descent of the water-tubs worked some very large pumps, which were

sufficient to lift all the mine water of the lower level into the

middle canal, and to keep the lower canal always at the proper height

for navigation.

The same tunnel of the Bridgwater canal was continued a considerable

way farther into Worsley Hill, until, under Walkden Moor, another

subterraneous canal or tunnel begins, at 35½ yards higher level, being

nearly 60 yards from the surface. From the surface two shafts were

sunk, one terminating in and over the upper tunnel or canal, and the

other in and over the middle or principal canal. There is another canal

still lower, and after passing close by the canal above. Between these

shafts a large drum was erected on the surface, with a brake-wheel and

a pair of strong ropes. An old account of the working of this tunnel

states, that “two boats being arrived at the shafts on the upper canal,

one of them loaded with boxes of limestone that was wanted at the

furnaces, and another with boxes of coals intended to be transferred

into an empty boat in the middle canal, the ends of the two ropes were

fastened to a box of coals and a box of limestone, when the superior

size and weight of the coal boxes drew the limestone to the surface,

to be there landed and deposited, at the same time as the box of coals

was deposited in the lower boat, ready to proceed on the canal to

Manchester or other places.”

This method was, in 1797, superseded by an inclined plane for letting

down the boats laden with coals from the higher to the middle level,

and returning the empty boats and boxes.

At Brierley Hill, near Coalbrook Dale, the extremity of a branch of

the Shropshire canal, great quantities of coal and iron, in crates

made of iron, were let down one of two shafts, which connected with

the termination of the canal above, and the ends of a railway in a

tunnel below, from which limestone in similar crates was drawn up the

other shaft to be placed in the boat. A barrel and brake-wheel were

fixed between the tops of the shafts, and cranes with jibs, by which

the crates could be raised and moved from the boat over the shaft or

the reverse. These shafts, which were 120 feet deep, were not found

to answer, in point of expense, so well as inclined planes, and Mr.

Telford informs us (‘Plymley’s Report,’ p. 296-307) that “inclined

planes have been substituted, on which crates of coal or iron pigs, or

goods descend, and draw up other crates containing limestone for the

use of the ironworks above, by means of ropes, a drum, and brake-wheel,

with a much less portion of manual labour, and more expedition, than

was done by the shafts above mentioned.”[282]

Marsden tunnel, on the Huddersfield Canal, is 5280 yards in length;

Sapperton, on the Thames and Severn, 4300 yards; Penfax, on the

Leominster and Kington, 3850 yards; Laplat, on the Dudley Canal, 3776

yards; Blisworth, on the Grand Junction Canal, 3080 yards; Ripley, on

the Cromford, 3000 yards; Dudley, on the Dudley Canal, 2926 yards;

Harecastle, on the Trent and Mersey canal, 2888 yards; Norwood, on

the Chesterfield Canal, 2850 yards; Westheath, on the Worcester and

Birmingham Canal, 2700 yards; Morwelham, on the Tavistock Canal, 2500

yards; Oxenhall, on the Hereford and Gloucester Canal, 2192 yards; and

Braunston, on the Grand Junction, 2045 yards.

The longest tunnels that have been proposed, besides those stated

above, were one of 5 miles on the once proposed extension of the

Manchester, Bolton, and Bury Canal to the Calder river; and one of 4¼

miles on the Portsmouth and Croydon Canal, through the chalk hills to

the south of the latter place.

The towns of Manchester, Kidderminster, and Southampton have been

partly tunnelled under by the Bridgwater, the Stafford and Worcester,

and the Southampton and Salisbury Canals respectively.

[Illustration:

_E & F N Spon London & New York_

“INK-PHOTO.” SPRAGUE & CO. LONDON.

DUDLEY TUNNEL ON THE BIRMINGHAM CANAL (SHOWING MEN IN POSITION FOR

“LEGGING”)]

There are several long tunnels on the Birmingham Canal system, having

an aggregate length of 6¼ miles. Two of these—the Dudley Tunnel and

the Netherton Tunnel—pass under the Rowley Hills, and are each about

two miles in length. The former was constructed in the last century.

The waterway is about nine feet in width, and there is no towing-path,

the boats being propelled by two men, lying on their backs on the boat,

their feet performing a sort of walking motion against the sides of the

tunnel, this is called “legging.” The Netherton Tunnel was constructed

in the year 1858; it has a waterway 17 feet in width on either side.

Both of these tunnels have, from time to time, been seriously injured

by mining operations, and in the case of the Netherton Tunnel, the

injury is stated to have been caused by the mine-owner illegally

working minerals that had been previously purchased by the canal

company. (See illustration of Dudley tunnel.)

VIADUCTS.

Sir Walter Scott spoke to Southey of the viaduct on the Ellesmere Canal

as the most impressive work of art he had ever seen. This viaduct is

situated about 4 miles to the north of Chirk, at the crossing of the

Dee, in the romantic vale of Llangollen. The north bank of the river

is very abrupt; but on the south side the acclivity is more gradual.

The lowest part of the valley in which the river runs is 127 feet

beneath the water-level of the canal; and it became a question with the

engineer, whether the valley was to be crossed, as originally intended,

by locking down one side and up the other which would have involved

seven or eight locks, or by carrying it directly across by means of an

aqueduct.

The aqueduct is approached on the south side by an embankment, 1500

feet in length, extending from the level of the waterway in the canal

until its perpendicular height at the “tip” is 97 feet. Thence it

is carried to the opposite side of the valley, over the river Dee,

upon piers supporting nineteen arches, extending for a length of 1007

feet. The height of the piers above the low water in the river is 121

feet. The lower part of each was built solid for 70 feet, all above

being hollow, for the purpose of saving masonry as well as ensuring

good workmanship. The outer walls of the hollow portion are only two

feet thick, with cross inner walls. Upon the top of the masonry was

set the cast iron trough for the canal, with its towing-path and side

rails, all accurately fitted and bolted together, forming a completely

watertight canal, with a waterway of 11 feet 10 inches, of which the

towing-path, standing upon iron pillars rising from the bed of the

canal, occupied 4 feet, 8 inches, leaving a space of 7 feet, 2 inches

for the boat. The whole cost of this part of the canal was 47,018_l._,

which was considered by Telford a moderate sum compared with what it

must have cost if executed after the ordinary manner. The aqueduct was

formally opened for traffic in 1805. “And thus,” says Telford, “has

been added a striking feature to the beautiful vale of Llangollen,

where formerly was the fastness of Owen Glendower, but which, now

cleared of its entangled woods, contains a useful line of intercourse

between England and Ireland; and the water drawn from the once sacred

Devon furnishes the means of distributing prosperity over the adjacent

land of the Saxons.”

The Barton Aqueduct on the Bridgwater Canal, is about 200 yards in

length, and 12 yards wide, the centre part being sustained by a bridge

of three semi-circular arches, the middle one being of 63 feet span.

It carries the canal over the Irwell at a height of 39 feet above the

river—this head room being sufficient to enable the largest barges to

pass underneath without lowering their masts. The bridge is entirely of

stone blocks, those on the faces being dressed on the front, beds, and

joints, and with cramped iron. The canal, in passing over the arches,

is confined within a puddled channel to prevent leakage, and is in as

good a state now as on the day on which it was completed.

The embankments formed across the low grounds on either side of the

Barton viaduct were considered very formidable works at that day. A

contemporary writer speaks of the embankment across Stretford meadows

as “an amazing bank of earth, 900 yards long, 112 feet in breadth

across the base, 24 feet at the top, and 17 feet high.” The greatest

difficulty anticipated was the holding of so large a body of water

within a hollow channel formed of soft materials. It was supposed at

first that the water would soak through the bank, which its weight

would soon burst, and wash away all before it. But Brindley, in the

course of his experience, had learnt something of the powers of clay

puddle to resist the passage of water, and he finished the bed of this

canal, so as to make it impervious to water.

Not the least difficult part of this undertaking was the formation of

the canal across Trafford Moss, where the weight of the embankment

pressed down and “blew up” the soft oozy stuff on either side; but the

difficulty was again overcome by clay puddle. Indeed, the execution

of these embankments by Brindley was regarded at that time as

something quite as extraordinary in their way as the erection of the

Barton Aqueduct itself.

EMBANKMENTS AND WEIRS.

Mr. Jebb has pointed out[283] that one of the most important duties

of the canal engineer, and certainly one of the most anxious, is to

take all practicable precautions for the prevention of any of the

embankments giving way by the overflow of water during heavy rainfalls.

In some districts at such times an enormous volume of water discharges

directly into the canal; this has to be got rid of. Self-acting weirs

are constructed at convenient points, and these are sufficient to keep

the water within bounds at ordinary times; but in times of flood other

means have to be used. The old canal “let-off,” as it was called,

consisted of a wooden frame (fixed in the bed of the canal), to which

was attached a hinged lid; this lid was pulled up by a chain fixed

to the lid when necessity required—that is, if the chain could be

found, and also sufficient power obtained for the purpose; for when the

let-off had not been used for a considerable time it became covered

with mud, and it was often as much as half-a-dozen men or a horse could

do to pull up; this accomplished, however, the water rushed out at once

with great force (as there was no means of regulating the discharge),

the sudden rush often causing trouble with the owners and occupiers

of the adjoining lands. Mr. Jebb has replaced some scores of these

let-offs by sluice valves of similar capacity, worked by racks and

pinions. The discharge of water can thus be exactly regulated, and one

man only is required to work them. The valves are tested every month to

see that they are in working order.

For the proper and economical maintenance of the towing paths, it is

necessary to have a staff of experienced men. Mr. Jebb recommends, as

a material for metalling, limestone _débris_, or what is locally known

in Birmingham as “raffil” or “bavin.” He finds that it sets soon, and

lasts for years if properly laid down—broken furnace cinders, covered

with good ashes, are largely used in the Black Country—the paths

should, of course, be well drained.

On the Birmingham canal, between Longford and Manchester, the sidelong

ground was cut down on the upper side and embanked upon the other by

means of the excavated earth. This was comparatively easy work; but

a matter of greater difficulty was to accommodate the streams which

flowed across the course of the canal. For instance, a stream called

Cornbrook was found too high to pass under the canal at its natural

level. Accordingly Brindley contrived a weir, over which the stream

fell into a large basin, from whence it flowed into a small one, open

at the bottom. From this point a culvert, constructed under the bed

of the canal, carried the waters across to a well, situated on its

further side, where the waters, rising up to their natural level, again

flowed away in their proper channel. A similar expedient was adopted at

the Manchester terminus of the canal, at the point at which it joins

the waters of the Medlock. It was a principle of Brindley’s never to

permit the waters of any river or brook to intermix with those of the

canal, except for the purpose of supply; as it was clear that in a time

of flood such intermingling would be a source of great danger to the

navigation. In order, therefore, to provide for the free passage of the

Medlock, without causing a rush into the canal, a weir was contrived,

306 yards in circumference, over which its waters flowed into a lower

level, and thence to a well several yards in depth, down which the

whole river fell. It was received at the bottom in a subterranean

passage, by which it passed into the river Irwell, close at hand.

In the earlier attempts made in the last century to deal with the

cataract of Trolhätta, in Sweden, it was determined to distribute the

whole fall of 113⅓ feet among three sluices only: the first to consist

of 28, the second of 52, and the third of 33⅓ feet. These sluices

were to be constructed alongside of the three cataracts, and were to

be each 18 feet wide by 72 in length. The work advanced successfully,

until the attempt to throw a weir across the river at the gulf of the

last cataract, to raise and retain the water above it. The impetuosity

with which the whole stream is precipitated had prevented the builders

from sufficiently examining the bottom. They had conjectured, from the

nature of the neighbouring mountains, that the bottom must be rock;

and it was further supposed that there could not be more than 10 feet

of water. Both these suppositions proved to be erroneous. The depth of

the water was from 20 to 25 feet at least, and the bottom was composed

of large detached stones, which were incapable of being fixed by any

efforts of art. The caissons of stone, although fastened together with

cramps 4 inches thick, and attached by great piles to the mountains on

both flanks, were swept off and dispersed by the impetuosity of the

current; and in this manner all the works were destroyed.

Subsequently it was determined to avoid the pass entirely, and

construct a canal 8200 feet long; and the total fall of 113⅓ feet was

to be distributed, in the space of the last 3000 feet, among seven

sluices or locks, each 36 feet in breadth by 200 in length.

The first sluice was to be 17⅓ feet in height; the others, 16 feet.

The first sluice was to stand alone; but the four following were to be

close to each other, as were also the last two. Between the fifth and

sixth sluice the canal was to be protected by a strong dyke against

the floods of the river. There was to be a great discharger between

the first sluice and the water entrance, not far from the centre; and

at the entrance itself two doors or gates, to lay the canal dry when

required. This plan proved more successful than the first.

Forty wholly removable, regulating weirs were constructed in the Seine

several years ago. When wholly closed up in summer, they maintain the

required depth of water for steamboat navigation. When wholly open

in floods, they cause no stoppage in the river surface. A remarkable

barrage mobile has been in action for several years at a place called

Port à l’Anglais, above Paris, and above the junction of the Seine and

the Marne. When all is open there is not a ripple on the river flowing

by. M. Gambuzat, the chief engineer of the river Seine, informed Mr.

Lynam that all those wholly removable regulating weirs in the Seine

were remarkably effective, and suitable for regulating that great

commercial river. Mr. Lynam declared that, if in July 1861, a month

previously to the great flood, the Killaloe weir-mound had been wholly

removed, and a wholly removable weir, like that in the Seine at Port

à l’Anglais, had been constructed, and subsequently been properly

manœuvred, during the month of August, none of the crops in the

level of the Shannon, above the Killaloe weir-mound, would have been

materially injured.[284]

The cost of high weirs on large rivers is considerable. For instance,

the most recent weir on the Seine at Poses, retaining a depth of 16½

feet of water, cost 151_l._ 5_s._ per lineal foot; and the Mulatière

weir, on the Saône at Lyons, retaining a depth of water of 10 feet,

cost 118_l._ 11_s._ 7_d._ per lineal foot.

On all navigations and canalised rivers liable to floods, the great

difficulty is to be able to pass away the water without impeding the

traffic, and without flooding the surrounding country. This has been

accomplished on the Weaver to a very great extent by means of what

are, practically, movable weirs, at Dutton, Saltersford, Hunts, and

Valeroyal. They are flood-gates, or sluices, capable of being lifted

clear of the water, and thus allowing an uninterrupted passage, and

consist of doors 15 feet by 14 feet deep, built of rolled iron beams

with timber sheathing. These are supported by masonry piers, and

are lifted by means of overhead gearing, so that the attendants are

entirely above water and on a permanent bridge. Friction is practically

dispensed with, owing to their working on rollers. The rollers hold

the doors from their seating, and would thus allow the passage of the

water. To prevent this, “stopwaters” have been introduced, consisting

of pieces of hard wood weighted at one end, until the specific gravity

is about the same as that of water; they then float vertically, and are

held in such a position that the pressure of the water forces them into

the angle formed between the door and the masonry.

This plan of sluice has practically reduced by one-half the flood level

at Northwich, and instead of having floods of 8 to 12 feet, the highest

that has occurred since their erection is one of 6 feet.

On the Aire and Calder Canal a form of sluice has been invented

and applied by Mr. Bartholomew which appears to have merits and

originality. A large culvert is made alongside the whole length of the

lock, with a very large sluice at the upper end, measuring 7 feet by

5 feet, the ordinary sluice being 2 or 3 feet square. Another sluice

is provided at the other end, and when this is closed and the lock is

empty, the upper sluice, which is self-balanced, like a throttle-valve,

is raised. Three orifices are made into the elongated lock, which are

arranged in such a way that the vessels are divided, and do not knock

against each other while in the lock. In emptying the lock, the upper

sluice is let down and the lower sluice is drawn, the water entering

the culvert through the orifices and discharging at the lower end. In

working the sluices, a man only requires to turn the handle and it

raises itself, while with three turns in the other direction it is

lowered. The locks on this system are 215 feet long, 22 feet wide, and

have 9 feet of water on the sills.

DAMS.

The proposed dam on the Nicaraguan Canal is to be of concrete, faced

with timber, and will be 1225 feet long on the crest, and 52 feet

high. The embankment will be 6500 feet long and 51 feet high in the

centre. There are, however, much larger dams than this. Of masonry

dams, Verviers, a small city of Belgium, near the frontier of Prussia,

with a population of about 38,000, has one—that of Gilleppe—154 feet

high and 771 feet long. The water supply of the town of St. Chaumonde,

in France, has a dam about 140 feet high, and the water supply of St.

Etienne is held by the Furens dam, 170 feet high.

The Villar dam, 162 feet high, holds the water supply of Madrid and

other dams in Spain, some of them dating back to Moorish days—Puentes,

Alicante, Val de Infierno, Nijar, Elche, and Almanza range from 164

feet to 68 feet in height. In England the Vyrnwy dam, at the Liverpool

waterworks is 136 feet high and 1255 feet long. The San Francisco

waterworks dam, 170 feet high and 700 feet long, and the Quaker Bridge

dam, 278 feet high and 1300 feet long, will, when built, be still

larger.

Of earthen dams or embankments, some of the most notable are the

Montaubry dam, on the Canal du Centre, 54 feet high; the dam, 66 feet

high, by which the water supply of Dublin is impounded; the reservoir

dam of the Bolton waterworks, England, over 120 feet high; the

Oued Muerad dam in Algeria, 95 feet high. In India and Ceylon such

examples are very numerous; the embankment of the Ashti reservoir is

58 feet high and 12,709 feet long; the Karakvasla dam is over 70 feet

high; the Tansa reservoir dam (water supply of Bombay) is to be 8500

feet long and 118 feet high; the embankment of the Cummum tank in the

Madras Presidency is 102 feet high, and although it ranks among the

earliest works of Hindoo history, it is still in such condition as

to fulfil its original intention. In Ceylon there are old tanks with

embankments from 3 to 12 miles long and 50 feet to 70 feet high.

The materials used for the construction of a weir or dam across a

river are principally earth, timber, fascines, stone, &c. The most

simple form of dam is that made of gravel protected by fascines kept

in place by piles. Such dams are principally used for temporary

works. Dams are often made of timber, stones, and earth combined, and

covered with planking laid parallel to the current, and the bottom of

the channel at the foot on the downstream side should be protected

by an apron formed of a platform of planks resting on piles, or by a

stone pitching. Dams of this kind built of dry stone and timber often

do not become weirs except during floods; that is to say, the water

does not pass over their crests except at such times, and at other

seasons of the year any surplus finds its way through the interstices

between the stones.

Dams may be built of caissons of strong timber, filled with loose

stones and covered with planking; others are filled with earth instead.

A recent writer states that weirs of solid masonry, like other

hydraulic works, should be founded on the natural ground on a bed of

concrete, or on piles, according to circumstances. The masonry may be

built in cement or hydraulic lime; the face-work is usually in dressed

stone or blocks. The stones, besides being fastened together by metal

cramps, are sometimes bonded by dovetailing.

A good example of a masonry weir is that built across the Dora Baltea

for obtaining a supply of water for the subsidiary canal of the Canal

Cavour. This work consists of a mass of concrete faced with ashlar and

blocks in courses roughly dressed. The crest is 1·20 metre in width,

and the total length 200 metres. This dam cost 237,682 francs, or at

the rate of 1188·41 francs per lineal metre. A layer of concrete alone

forms a very effectual protection to a river or canal embankment.

In rivers subject to excessive floods a rock-work consisting of

large irregular-shaped blocks of stone—not less than one-third of a

cubic metre each—is exceedingly useful for protecting the bottom of

embankments or walls from scour.

FOOTNOTES:

[282] Paper by Mr. G. R. Jebb in the ‘Journal of the Society of

Arts,’ for 1888.

[283] Paper on “The Maintenance of Canals,” in the ‘Journal of the

Society of Arts’ for 1888.

[284] Paper read before the British Association, 1878,.

CHAPTER XXXI.

SPEED OF TRANSPORT.

All other things being equal, the system of transport that is able to

afford the greatest average speed will be certain to command the lion’s

share of business. There are, however, both natural and economical

limits to speed, alike on water and on land. The natural limit up to

the present time may be put at 50 miles an hour for railway travelling,

20 knots per hour for sea transport, and four or five miles an hour for

canal navigation. The economical limits are, however, very different.

A goods train cannot be worked economically at a greater speed than 20

to 25 miles an hour, and many railway companies decline to work their

mineral traffic at a higher speed than 15 miles. At sea, the ordinary

rate for a cargo-carrying steamer will vary from 10 to 14 knots, but

seldom exceeds the latter figure. On an artificial waterway it is

not possible, even in the absence of locks or other obstructions, to

maintain a higher rate of speed than 4 or 5 miles without doing serious

injury to the banks.

A very excellent paper on the rate of speed which it is possible or

usual to attain in canal navigation, under varying conditions of

towage, locks, depth, and other elements that influence the question,

was submitted to the Institution of Civil Engineers some years ago by

the late Mr. Conder, who devoted much attention to the subject.[285]

On the Belgian canals, where human labour is employed for towage, the

rate of speed does not exceed 1 to 1⅓ mile per hour, against 2⅔ miles

on the same canals with steam towage. On the Grand Junction Canal the

speed varies from 3 to 3½ miles, and on the Rotterdam Canal it is 5

miles per hour. The limiting speed on the Suez Canal is about 5¾ miles

per hour, but there is a loss of speed on that waterway, due to the

trapezoidal form of section, which is estimated at about half a mile

per hour. The average retardation of speed on English canals, due to

locks, has been calculated at between 1·75 and 1·95 minute per mile.

The greatest difficulty that lies in the way of extending canal

navigation is the uneven character of the country that has usually to

be traversed, and the consequent necessity of overcoming elevations

and depressions by locks, lifts, inclines, or other costly mechanical

devices. In crossing England, between the Thames and the Severn, a

height of 358 feet has to be overcome on the 204 miles of the Wilts and

Berks route; a height of 474 feet on the 180 miles of the Kennett and

Avon route; and a height of 392 feet on the 206 miles of the Thames

and Severn Canal route. The average difference of level on these

routes, counting ascent and descent, is 4·14 feet per mile, or a little

more than one-fourth of the ruling gradient laid down by Mr. Robert

Stephenson for the London and Birmingham Railway. Canal lifts would

overcome these differences better than locks, but then they are much

more costly, and perhaps not, on the whole, so convenient. Tunnelling

or cutting, as in the case of a railway, is in a large number of cases

out of the question. There is, therefore, only the alternative of

making locks, which involve tedious delays, and add largely to the cost

of transport.

In the year 1825, the same year that saw the opening of the first

passenger railway, Charles Maclaren undertook to prove that for all

velocities above 4 miles an hour, a railway was much more economical

than a canal. At 6 miles an hour he calculated that nearly three times

as much power would be required to move an equal mass on a canal, while

at 20 miles an hour he computed that twenty-four times as much power

would be required. At 8 miles per hour the same writer estimated that

the resistance in water increased so much that two horses on a road

would do as much as one on a canal, although at 2 miles an hour the

same amount of horse power that is required to drag one ton on a good

road would drag 30 tons on a canal.

It is not a little amusing, in the light of our present experience, to

find this author gravely stating that “the tenor of the evidence given

before the Parliamentary Committee (on steam navigation) renders it

extremely doubtful whether any vessel could be constructed that would

bear an engine (with fuel) capable of impelling her at the rate of 12

miles an hour without the help of wind or tide;” while as for railway

speed, he asserted that, “in speaking of 20 miles an hour it is not

meant that this velocity will be found practicable at first, or even

that it should be attempted.”

Canal engineers have found that where they can concentrate the rise

of level on a canal by the use of lifts, or inclined planes, they can

usually obtain a considerable increase of speed. Thus, on the river

Weaver, a height of 51 feet is cleared by the Anderton lift in about

eight minutes. On the incline of the Morris Canal, again, a height of

51 feet is overcome in three and a half minutes; while on the Forth and

Clyde Canal the Blackhill incline enables a height of 96 feet to be

overcome in ten minutes. This averages about three times the speed that

could be attained in overcoming the same rise or fall by means of locks.

We have already seen it computed that there are in Great Britain one

lock to every 1·37 mile of canal.[286] Mr. Conder has calculated that

there is, at this rate, “an average rise or fall for the system, as far

as it is represented by the time returned, of 5·84 feet per mile.” On

the more uneven sections a running speed of 5 knots, or 5·76 statute

miles per hour, will be reduced on an ordinary English canal by the

delays caused by the locks, to a speed of 4·9 miles per hour. In other

words, the rate of speed should be nearly double the speed of prompt

canal service at the present time. Between Gloucester and Birmingham

the merchandise sent by river and canal is delivered as quickly as that

despatched by railway.[287]

Speed on canals is regulated by the effect of breaking waves on their

banks. In narrow canals or rivers, such a wave first appears at from 3

to 3½ miles per hour, and it has been found that at 4 miles per hour it

exercises an injurious effect on the banks of the canal. When the speed

is increased to 5 miles an hour, the effect becomes much more marked,

the waves breaking over the towing-path, and rendering navigation

destructive.

Mr. Conder appeared to think that a speed of 5 miles an hour, or 8·37

feet per second, which is the limit of speed fixed for the Suez Canal,

may be taken as the normal speed to be sought on the canals of England;

and he adds that, “on the determination of the normal speed, and of

the tonnage of the boats to be accommodated, will depend not only

the steam-power required, but the sections of the canals and of the

dimensions of the locks.”[288]

In Sweden, as well as in Holland, where the channels are narrow, the

usual speed is 3½ miles per hour, but 5 miles an hour is frequently

attained, the difference depending on the area of cross-section.

In curves and shallows, in narrow canals or rivers, a breaking wave

first appears at from 3 to 3½ miles per hour. At 4 miles an hour the

effect of the wave on the banks becomes injurious. At 5 miles an hour

the wave increases, breaking over the towing-path, and being followed

by other waves in succession. In parts of the Clyde, from 120 to 150

feet wide, and about 10 feet deep, vessels of from 120 to 150 feet

long, with from 16 to 18 feet beam, and from 5 to 6 feet draught, are

propelled by engines of from 80 to 100 horse-power, at a speed of from

8 to 9 miles per hour. At this speed a surge rises at from 2 to 3 miles

ahead, and a wave is caused, which measures 8 or 9 feet from the crest

to the bottom of the trough.[289]

A speed of 5 knots per hour, or 8·37 feet per second, corresponding to

a head of 1·08 foot of water, is the limit of speed fixed for the Suez

Canal. This may perhaps be taken as the normal speed to be sought on

the canals of England. On the determination of the normal speed, and of

the tonnage of the boats to be accommodated, will depend, not only the

steam-power required, but the section of the canals and the dimension

of the locks. A speed of 30 miles a day, including stoppages, is even

now attainable on English canals.

The rate of speed on a canal is, of course, affected by the size as

well as by the number of the locks, by the depth of the waterway,

and by the tonnage of the craft that navigates it. On some English

canals there is a lock to be passed through about every half mile, and

the rate of speed is under a mile per hour.[290] On others, however, a

speed of 3 miles may be kept up pretty well. The economical rate of

speed is often put at 2½ miles. At a higher rate of speed the cost of

maintenance of the canal would be likely to counterbalance the saving

due to quicker transit. Speed is also affected by differences of gauge,

which in some cases compels cargo to be transhipped with much loss of

time that might be obviated with a uniform gauge.

The size of craft which can traverse a through route depends on the

least navigable depth in the canal and over the sills of the locks, and

the least width and length of any lock along the route. Unfortunately,

very few through canal routes exist in England which are not obstructed

by some narrow locks, or shallow portions of canal, rendering the

comparatively good width and depth of the remainder quite unavailable

for a larger craft. In France, the same want of uniformity of gauge on

the waterways has hitherto existed; but as almost all the waterways

are under the control of the State, improvements and extensions have

been constantly in hand; and we have already seen that in 1879 a law

was passed for providing a uniform depth of 6½ feet, locks 126⅔ feet

long and 17 feet wide, and a clear height of 12 feet under the bridges,

throughout the principal lines of waterway in France. The works for

securing this uniformity are being gradually carried out; and when they

have been completed, 300-ton barges, 126⅓ feet long, 16½ feet wide, and

6 feet draught, will be able to traverse all the principal waterways of

the country.

The depth of English canals ranges, for the most part, from 3 feet to

5 feet; but the Severn navigation to Gloucester affords a depth of 6

feet; the Gloucester and Berkeley Canal, 15 feet; the Aire and Calder

navigation, 9 feet; and the Forth and Clyde Canal, 10 feet. The locks

range in size from 72 feet length, 7 feet width, and 3½ feet depth of

water over the sills, up to 215 feet by 22 feet by 9 feet on the Aire

and Calder navigation.

It goes without saying that if the average rate of speed that can be

maintained on a canal does not exceed 3 or 4 miles per hour, the canal

will never compete with the railway as a quick means of transport. The

use of such waterways would thereby be limited to heavy traffic, in the

delivery of which time was a matter of minor importance. But more than

two-thirds of all the traffic carried on British railways, and indeed

on railways generally, is of this character. The question thereupon

arises, Is the economy of water transport sufficient to compensate for

a slower rate of speed? Sir James Allport, who, of course, held a brief

for the railway interest, informed the Canal Committee of 1883 that the

railway engine would accomplish ten times as much work as a canal boat,

and would do in an hour what would occupy a day on a canal.[291] Mr. F.

Morton, on the other hand, speaking as a railway and canal carrier of

experience, declared that, in conveying minerals between North and

South Staffordshire, railway waggons and canal boats averaged about the

same time—seven to eight days.[292] However this may be, there can be no

doubt that where canal transport is efficient it is much cheaper, and

that is the main thing for the trader.

Mr. Bartholomew has made an elaborate series of inquiries and

experiments upon the Aire and Calder Canal, with a view to determine

the cost of different systems of canal haulage, and has found

the results to be as under:—

With steam tugs, carrying cargoes, 1/34_d._ per ton per mile.

” ” ” not carrying cargoes, 1/7_d._ ” ”

” horse haulage, ⅕_d._ ” ”

The lowest of these charges is not comparable with the lowest railway

rate of which we have ever heard, while the highest is much below

what railway managers usually state to be the cost of carrying their

cheapest traffic.

It will, however, be impossible either to greatly increase speed

or to reduce rates on British canals unless the system undergoes

reconstruction. The rates given above for the Aire and Calder Canal

are no doubt exceptionally low, because that is one of the best

managed and best equipped canals in the country. On the average of

the English canals the cost of transport will be a good deal more,

and it must continue to be so until they have been brought up to the

level of efficiency maintained on the Aire and Calder. In the majority

of the canals of England it is either impossible, or economically

impracticable, to employ steam power, without which the ultimate extent

of possible economy cannot be realised. Mr. F. Morton has correctly

expressed the position of affairs when he stated that “the present

method of employing steam on narrow canals is about comparable to a

locomotive capable of taking thirty loaded waggons, having only four

or five behind her.” This must remain so until steps have been taken

to do in England what has been done in France and other countries—to

secure a uniform gauge and a depth sufficiently great to enable boats

to be navigated that carry loads of 100 to 200 tons, so that the canal

boats may be the counterpart of a railway train. If the Aire and Calder

system of working trains of boats, carrying 700 to 900 tons per train

can be introduced, so much the better.

FOOTNOTES:

[285] Conder on “Speed on Canals,” ‘Minutes of Proceedings,’ vol. 76.

[286] ‘Report of the Select Committee on Canals,’ p. 125.

[287] ‘Minutes of Proceedings of the I. C. E.,’ vol. lxxvi. p. 171.

[288] Ibid., p. 169.

[289] ‘Minutes of Proceedings of the I. C. E.,’ vol. lxxvi. p. 168.

[290] Ibid., p. 161.

[291] Report, q. 1620-1622.

[292] Ibid., 2, 2617.

CHAPTER XXXII.

CANAL TRAFFIC: ITS CHARACTER AND ITS DENSITY.

There is a very prevalent impression that railways and canals have each

their proper and natural function in the transport of merchandise—the

railways in the carrying of goods of considerable intrinsic value, or

of a perishable character, in which speed is an element of value; and

the canals in conveying heavy merchandise, such as coal, iron ore, pig

iron, building stone, timber, and other traffic, of relatively low

intrinsic value, and incapable of being deteriorated by delay.

In accordance with this idea, the canal traffic of most European

countries has usually taken the form of coal, iron, and other heavy

merchandise, while the railways have carried goods that were charged a

high rate of freight, on the grounds that they were damageable, and of

high intrinsic value.

This, however, is by no means a universal rule. On many waterways, and

especially in countries which have limited railway facilities, like

Russia, canals are found as well adapted as railways to all purposes

of transport. On the canals of the United States, the canals compete

with the railways in carrying wheat and other agricultural produce.

On the Aire and Calder canal, the canal boats are adapted to carry,

and as a matter of fact do carry, considerable quantities of general

merchandise, as well as minerals.

The French Government and Chambers, guided by the well-informed

engineers of the Ponts et Chaussées, have controverted the idea that

there is necessarily any real rivalry between railways and canals.

“Each of these two ways of communication,” reported M. de Berigny to

the Chamber of Deputies in 1833, “has its distinct and special domain.”

“Nothing,” says another French writer, “is to-day more true. Almost

everywhere that navigable routes and railways run side by side, the

development of industry and commerce has been such that after a brief

crisis the traffic of the older line of communication has notably

increased. Far from being enemies, railways and canals aid one another

in the performance of their natural duties. The former transport

passengers, costly merchandise, manufactured products—all that cannot

endure long delay. The latter, on the other hand, transport raw

materials of small value, for the transport of which speed is of

secondary importance, which cannot bear high rates of charge, and which

in consequence do not form a remunerative traffic for railways.”[293]

“The delay of a week or a fortnight in the delivery of these articles,”

reported the Commission named by the Chamber of Deputies in 1878 to

examine the project for improving the inland navigation of France, “is

a matter of little importance, while the difference of freight for long

distances between the lowest rate at which a railway can carry and

that which is attainable on a canal is equal to half the price of the

goods.” “Coal,” the Commission stated, “cannot be carried on railways,

even for long distances, at a less cost than from 0·54_d._ to 0·62_d._

per ton per mile, but can be transported by canal for 0·22_d._ per ton

per mile.”

“In France, in Germany, in Belgium, and in England,” says another

writer,[294] “the round price of one-third of a penny per ton per mile

will pay for transport on canals of adequate section and volume

of traffic, and this price includes, not only a fair interest on

the capital, but also provision for sinking fund, which within a

determinable time will render these inland waterways the property of

the nation, to be used free of charge, except the trifling amount

necessary for maintenance of the works and attendance on the locks.

On a traffic of 600,000 tons per annum this charge does not exceed

0·022_d._ per ton per mile.” The cost of towing, to be borne by the

users of these national waterways, has been found to be as low as from

0·065 to 0·079 per ton per mile for horse towing in Belgium, including

the return of empty boats.

There is no record of the traffic that is carried on the canals of the

United Kingdom at the present time. On the Birmingham Canal, which

has a mileage of 162 miles, and some hundreds of private basins, the

tonnage carried in 1887 was not less than 7,000,000 tons. This is

an average of about 43,200 tons per mile, and if the whole of the

canals constructed in the United Kingdom had been equally useful and

successful, the total quantity of traffic carried on the 3000 miles

of canals constructed would have been close on 130,000,000 of tons,

or more than one-half of the total tonnage carried on the railways of

the United Kingdom in 1887. Of course, however, the Birmingham Canal

traffic is altogether exceptional, as is also that of the Bridgwater

Canal, and the Aire and Calder Navigations. These three canal systems

compete very successfully with the railways for the heavy traffic of

the districts through which they pass, and have been able for years to

earn large dividends, with comparatively low rates of freight.[295]

There is a widespread belief that railway transport represents a

very considerable proportion of the total ultimate cost of the heavy

traffic carried in this country. Of some descriptions of heavy traffic

this is no doubt true. It is not, however, equally true of mineral

traffic. The average receipts earned by the railway companies per ton

of minerals transported in 1888, irrespective of distance, was 1·6_s._

On the great bulk of the coal and iron ore carried, it must have been

very much less, seeing that a large quantity of coal—as for example

the supply of London, which is alone an item of over seven millions of

tons a year—is carried for over a hundred and fifty miles at 6_s._ to

7_s._ per ton freight.[296] There is no similar record of traffic for

other countries. In the United States the census returns show that in

1880, 89½ millions of tons of coal were carried on all the railways

then open. The gross income earned thereby is not, however, separately

stated, although it may be possible to arrive approximately at the

figure we want by taking the statistics that are given for the group

of States of which New York, Pennsylvania, and Ohio are the chief.

In this group 192 millions of tons were carried in 1880, of which 76

millions of tons were coal. The revenue derived therefrom was 208

millions of dollars, so that the average amount paid to the railways

per ton carried was 4·3_s._, or nearly three times as much as in Great

Britain.[297]

The chief canal in the Russian empire is that of Vishni Volotchok,

which connects the Baltic and the Caspian Seas, and thereby affords

communication with Siberia and China. In the early years of the century

the principal part of the internal trade of the empire was conveyed

along this canal. In 1777, the number of barges that passed through

this canal was stated to be 2641. Twenty years later, the number of

vessels that navigated its waters was returned at 6264,[298] conveying

merchandise of the weight of over 8 millions of poods, and yielding

tolls of the amount of 34,192 roubles (6840_l._). The tendency of late

years has been to divert the lighter and more expensive traffic from

the canals to the railways where the latter were available; but to this

day, all descriptions of traffic make use of the canals of Russia, and

usually at remarkably low rates of freight.

As we have elsewhere pointed out, however, the preference for one form

of transport over another is not always a mere matter of rates. If

proof were needed of this fact, it would be furnished to the fullest

extent by studying the history of the struggle that has been waged

for many years past between the New York State Canals and the various

railway systems that connect that city with Chicago, for the wheat

supplies intended for export to Europe and consumption in the Eastern

States. The rates of freight have all along been much lower on the

lakes and the Erie Canal than on the railways. Usually, indeed, the

water transport has not cost more than one-half what has been charged

by rail. And yet the amount of traffic forwarded by lake, river, and

canal has diminished, while that carried by railway has enormously

increased. In other words, freighters have been for some years past

content to pay 12 or 14 cents per bushel to the railway companies when

the canal companies offered to perform the same service for 6 or 7

cents. The question naturally arises—Why should the canals not absorb

the whole traffic? The answer is that the inconvenience and uncertainty

due to interrupted navigation, and the inevitable slower rate of speed,

have been sufficient to induce the American wheat grower to pay double

the sum in order that he might secure quick and certain despatch. The

same phenomena may be witnessed elsewhere. But much, of course, depends

upon the traffic. Wheat may afford to pay a few cents more under the

circumstance stated, when coal and lumber could not. It is manifestly

more important that wheat should be carried to its ultimate destination

in good condition, and without preventable delay.

_The Density of Traffic on Waterways._—One of the most interesting

problems connected with the working of either railways or waterways,

is that of the density of the traffic transported, or, in other words,

the quantity carried, relatively to the length of the line. The law

of averages, which is very often inapplicable, and likely to lead to

erroneous conclusions, is, in the case of the density of traffic,

capable of being applied with some amount of success. But even in

apparently so simple a matter as this, it must be applied with caution,

and with certain rather important reservations. It must be borne in

mind, for example, that as railways are performing the double function

of transporting both passengers and goods, their traffic per mile,

measured in terms of merchandise, cannot be fairly compared with that

of canals, which carry goods traffic alone. Nor can the traffic of a

canal, where the speed is necessarily slow, be rightly compared with

that of a river like the Thames or the Rhine, where there is almost

no limit to the speed that may be safely applied, except the limits

imposed by mechanical laws.

The density of traffic on waterways has a very wide range of variation.

On the Thames, where the annual tonnage of the entrances and clearances

of vessels amounts to about 18,000,000 of tons a year, it may be put at

something like 1,000,000 tons per mile, if we take the average distance

between the mouth of the river and the docks as about 18 miles. This,

however, is a case that stands alone. No other waterway has anything

like the same amount of traffic, and for purposes of comparison the

Thames may be disregarded entirely. The same remark applies to the

Mersey.

The complete statistics of the inland navigations of France and Belgium

enable comparisons to be made of the different waterways, which are

very interesting. We find that some canals have a very considerable

traffic, while others have only a traffic of limited dimensions. From

recent returns relative to the canals of France, we have abstracted

particulars which illustrate these differences, and which are given in

the tables that follow.

The following French canals have an exceptional density of traffic:—

DENSITY OF TRAFFIC ON SOME SHORT CANALS IN FRANCE IN 1886.

─────────────────────────────────┬────────┬──────────┬─────────

│ │ Tons of │ Average

│ Length │ Traffic │ Traffic

Name of Canal. │ in │ Carried │ per Km.

│ Kms. │ in 1886. │ in Tons.

─────────────────────────────────┼────────┼──────────┼─────────

Aire (Baudin to Aire) │ 28 │ 2,255,000│ 80,535

Bourbourg (Guindal to Dunkerque) │ 13 │ 1,042,000│ 80,123

St. Denis (Paris to La Briche) │ 4 │ 1,722,000│ 430,500

Deûle, Haute │ 38 │ 3,652,000│ 96,105

Mons to Condé │ 3 │ 705,000│ 235,000

Neuffossé (Aire to St. Omer) │ 11 │ 1,198,000│ 108,999

Oise (Janville to Chauny) │ 21 │ 2,804,000│ 133,523

St. Quentin (Cambrai to Chauny) │ 58 │ 3,606,000│ 62,172

Seusée (Etrun to Courchelettes) │ 16 │ 1,955,000│ 112,187

├────────┼──────────┼─────────

Totals and average │ 192 │18,939,000│ 98,129

─────────────────────────────────┴────────┴──────────┴─────────

These are, for the most part, short waterways connecting important

centres of industry or population. The larger canals, however,

are by no means so well provided with traffic, and on some of them

the traffic is almost ludicrously small. On 1125 miles of these

longer canals, the average density of traffic per kilometre was only

2724 tons, as compared with 98,129 tons per kilometre on the 192

kilometres of shorter waterways contained in the above table. The

particulars are appended:—

STATEMENT SHOWING THE DENSITY OF TRAFFIC ON SOME OF THE

LONGEST CANALS IN FRANCE IN 1886.

───────────────────────────────────────┬────────┬──────────┬────────

│ │ Tons of │ Average

│ Length │ Traffic │ Traffic

Name of Canal. │ in │ Carried │ per Km.

│ Kms. │ in 1886. │ in Tons.

───────────────────────────────────────┼────────┼──────────┼────────

Berry (Fontblisse to Noyers) │ 88 │ 384,181 │ 4,365

Burgogne (Laroche to St. Jean de Losne)│ 151 │ 424,559 │ 2,811

Est (Belgian frontier to Troussey) │ 170 │ 648,471 │ 3,820

Est (from Messlin to the Saône) │ 75 │ 276,065 │ 3,680

Garonne (Toulouse to Castel) │ 134 │ 243,815 │ 1,819

Midi (Toulouse to Thau) │ 152 │ 167,985 │ 1,105

Nantes and Brest │ 167 │ 111,558 │ 668

Ourcq (Port-au-Perches to Paris) │ 68 │ 528,048 │ 7,765

Rhone au Rhin (to German frontier) │ 120 │ 279,957 │ 2,332

├────────┼──────────┼────────

Totals and average │ 1,125 │3,064,639 │ 2,724

───────────────────────────────────────┴────────┴──────────┴────────

FOOTNOTES:

[293] M. Picard in ‘Les Chemins de Fer de France,’ in 1884.

[294] ‘Edinburgh Review,’ for October, 1882.

[295] Paper by Mr. G. R. Jebb, on “The Maintenance of Canals, with

special reference to Mining Districts,” ‘Journal of Society of Arts,’

1888.

[296] The London coal supply is largely carried, in competition with

the sea, at the remarkably low rate of ·5_d._ per ton per mile, and

even less.

[297] ‘Report of the Tenth Census,’ vol. iv. p. 133.

[298] Of this number there were 3958 barques, 382 half barques, 248

boats, 1676 floats; 6264 in all.

CHAPTER XXXIII.

THE MAKING OF ARTIFICIAL WATERWAYS.

“When, with sounds of smother’d thunder,

On some night of rain,

Lake and river break asunder

Winter’s weakened chain;

Down the wild March flood shall bear them,

To the saw mill’s wheel,

Or where steam, the slave, shall tear them,

With his teeth of steel.”

—_Whittier._

There is no direction in which the triumph of man over the material

forces with which he has to deal may be studied with greater advantage,

even by the casual reader and the unscientific observer, than in that

of the making of railways, the deepening or widening of rivers, the

construction of artificial waterways, and the maintenance of ports and

harbours. Each of these operations involves the employment of machinery

and appliances that were quite unknown to our forefathers. The modern

processes of excavation of the soil, in order to form or deepen the bed

of a waterway, or of the construction of an embankment, in order that

a railway or a canal may be carried above the level of the surrounding

country, are now so familiar and commonplace, that we are accustomed

to think but little of the slow and laborious steps whereby the means

of carrying them out have been evolved from the necessities, the

experience, and the scientific acquirements of modern times. Had the

engineers of the present day been limited to the rude and imperfect

appliances that they had alone at command a hundred years ago, such

works as the making of the Suez, the Panama, and the Manchester canals;

the deepening of the harbours that are now scattered up and down

our extensive coast-line; and the adaptation to the requirements of

modern shipping of the navigable rivers that have done so much for our

maritime supremacy would have been all but impossible.

Let us take only a single instance, by way of illustration, and it

shall be one that is very familiar, and easily capable of verification.

On the works of the Manchester Ship Canal, in a length of only 35½miles,

and over a comparatively level country, 45 million cubic yards of

excavation are necessary. More than one-half of this vast quantity

had been accomplished up to the end of 1889, by the employment, of 95

steam navvies or dredgers, 180 cranes, 160 locomotives, using 205 miles

of temporary railway, 5500 waggons, and 220 portable and other steam

engines, the number of employés being about 4000. To have executed this

amount of work by any other system would have involved, perhaps, twenty

times the amount of labour and more than twenty times the amount of

time, if we are to judge by the accounts that have been handed down to

us from ancient records as to the period over which the great works of

antiquity extended.

It is not, however, in the mere work of excavation, that economy and

progress have been effected. Another notable economy has resulted from

the employment of large hopper barges, whereby 1000 tons or more of

the dredged or excavated material may at once be removed to sea. The

economy resulting from this source is stated to have enabled a saving

of 40,000_l._ per annum to be effected in the works connected with

the port of Dublin, without which economy the improvements actually

carried out there would have been impossible.[299] In larger spheres

of operations the economy must, of course, have been correspondingly

greater.

Ralph Dodd appears to have contrived a machine to be worked by men, by

means of levers, for excavating canals, which was tried in the year

1792, in the deep cutting at Dawley, near Hayes, on the Grand Junction

Canal. Carne’s machine, for the same purpose, but worked by a horse at

length, appears to have been used in 1794, in the deep cutting near

Cofton Hacket, on the Worcester and Birmingham Canal. In the ‘Monthly

Magazine’ (vol. ii., page 594) we have the following account of the

operation of E. Haskew’s patent excavator:—

“This machine takes the soil from the bottom of the canal at 40 feet

deep with equal facility as at six feet from the surface. One of them

is at work upon the Gloucester and Berkeley Canal; by the assistance

of two men only it removes 1400 loaded barrows from the bottom of the

canal, to the distance of 40 feet, in twelve hours, and is so contrived

as to take up the loaded barrows, leave them at the top, bring down the

empty ones in regular rotation, and leave them at the bottom; it can be

moved along the canal to the distance of 26 yards in ten minutes by the

two men that work it.” In October 1793 Joseph Sparrow took out a patent

for a machine, consisting of a box, with its bottom opening on hinges,

suspended by a sort of universal gib or crane, the whole moving upon

wheels, which he strongly recommended for elevating and discharging the

soil dug out of the canal.

Among the most considerable deep cuttings in England up to the end of

the last century were those at Ashton, on the Lancaster; Tring, on

the Grand Junction; Coston Hacket, on the Worcester and Birmingham;

Burbage, on the Kennet and Avon; Littleborough, on the Rochdale; and

Smethwick, on the old Birmingham canals.

As the development of the processes of excavation and embankment forms

one of the fullest chapters in the history of both civil and mechanical

engineering, we shall not here presume to enter upon it at any length.

A history of dredgers would be almost as serious an undertaking as

a history of steamboats or locomotive engines. Their actual number

is legion; but the dredgers that are now used on a large scale are

comparatively few. Of course, everything depends upon the amount of

work to be done, its locality, and other surrounding circumstances; but

for operations on a scale of magnitude, few dredgers appear to have a

better reputation than that which bears the name of Couvreux.

In the case of the improvement works undertaken on the Belgian Ship

Canal, the Couvreux excavator removed, in 1875, 218,400 cubic yards of

material in 166 days, being at the rate of 1316 cubic yards per day.

Notwithstanding this, hand labour was very largely employed upon the

work, a large quantity of water having to be dealt with at a depth of

about 10 feet.

The earth excavated was carried to spoil, and in many cases was

employed to form dykes enclosing large areas, which served as

receptacles for the semi-liquid material excavated by the dredging

machines with the long conductors; the Couvreux excavator used had

already done service on the Danube regulation works. The material with

which it had to deal in this case was, however, of a more difficult

nature, being a fine sand, charged with water, and very adherent. The

length of track laid for the excavator was about three miles along the

side of the old canal, which had been previously lowered to the level

of the water. The floating dredgers employed were 88 feet 7 inches

long, 19 feet 8 inches wide, and 7 feet 9 inches deep; the arm was 39

feet 4 inches long, and passed through the hull. The form of the

buckets was the same as that used at the Vienna regulation works,

but the staging was higher, the axis of the driving-wheel of the

bucket-chain being 26 feet 3 inches above the water-level. This

increased elevation was necessary on account of the different methods

employed for transporting the dredged material. To a large extent

the same method of transport that was adopted on the Suez Canal was

repeated in the case of the Belgian Canal Works. The conductor used

allowed the sand and mud excavated to be delivered at a point 140 feet

and 150 feet from the dredge, and at a height of 13 feet from the

water-line. The excavated materials fell into the concave conductor

6 feet below the point of their discharge, and on falling they

encountered the action of a stream of water which was constantly pumped

along the conductor, and by which they were converted into semi-liquid

mud. The slope of the conductors was generally 1 in 2000; it was

supported by cables attached to a staging connected with the framing

of the dredge, and the base of which rests on the deck of the vessel.

The conductor is counterbalanced by a platform, on which was placed the

portable engine and pump used for lifting the water into the conductor.

This platform was suspended to the dredge in the same manner as the

conductor itself. The general arrangement is shown on the engraving at

p. 453. The supply and the maximum incline depend on the facility of

disintegrating the ground, and on the quantity of water contained in

the mixture. The proportions generally used were three parts of water

to one of sand.

When the excavators met with compact clay which disintegrates slowly,

or not at all, under the action of the water, the fragments raised

were carried along in the current running through the conductor, but,

of course, at a slower rate than the sand. Stones even of large size

were also easily dealt with in the same manner. These materials were,

however, only occasionally met with, the ground being chiefly composed

of the fine sand, already referred to, mixed with a little clay, which

was easily reduced to the required consistency.

Deposits were formed for the reception of the excavated material, which

constitute filtering basins enclosed within vaults formed by the solid

materials previously removed. Where it was not possible to discharge

direct into their depots by the long conductor, barges received the mud

and carried it to a convenient destination.

[Illustration: SYSTEM OF EXCAVATOR ADOPTED ON THE GHENT AND

TERNEUZEN CANAL.]

The floating excavators were placed on two hulls carrying an iron

framework, on which the staging supporting the bucket wheel was

mounted. The engines and boiler were installed in one of the hulls,

and in the other was placed the pump and engine for driving it. The

upper level of the conductor was 78 inches below the bucket wheel.

The conductor, 100 feet in length, was of the section corresponding

to that of the buckets, 17¾ inches in diameter. It was supported by

three cables attached to a staging, resting on the boat and secured

to the bucket-wheel frame. The slope was 1 in 400, which allowed the

material to be deposited at a level 22 feet 3 inches above that of the

water. These excavators performed excellent duty; they could be easily

transported from place to place, and were not affected by changes in

the water level.

The position of the depots often involved the necessity of transporting

the dredged material distances of 1200 or 1500 feet from the excavator.

In such cases supplementary conductors were added. These were open, and

were laid on the ground with a slope of 1 in 1000. Not unfrequently

large blocks of old masonry, which formed the _revetment_ of the sides

of the canal, were raised by the excavator. These were generally

carried down with the rest of the material, but occasionally they

stopped, choking the channel, and requiring hand labour to remove them.

When this mode of transport could not be adopted, barges were employed

to receive the dredged material and remove it to convenient points of

discharge. These boats were built of iron, with double sides; they were

82 feet long and 15 feet 8 inches wide. Barges of similar dimensions

were employed in the formation of earthworks under water, which were

required at various parts of the canal. In these boats, holes 12 inches

in diameter were placed 13 feet apart, iron tubes connecting the inner

and outer shells. These holes were closed by means of valves while the

boat was being loaded, and they were opened when it was brought over

the place where it was desired to discharge.

[Illustration: EXCAVATOR ON THE GHENT AND TERNEUZEN CANAL.]

One of the most remarkable and successful dredgers of the present day

is employed on the Montreal harbour and ship channel improvements, and

is known as the Canadian dredger. This machine, instead of being like

the ordinary St. Lawrence dredgers, attended by a tug and scows, has

an internal mud-hopper, and is self-propelling, thus being in fact

dredger, tug, and scows combined, and requiring a proportionately

large hull. In a recent comparison of this dredger with one employed

at Otago, it was stated that the Otago dredger cuts to 35 feet deep,

as do those of the St. Lawrence, but the latter have buckets a third

larger, and arranged so as to be very nearly twice as effective. The

Otago dredger is reported to have raised at the rate of 400 tons an

hour, while filling her hopper, but the improved St. Lawrence dredgers

easily fill their scows at the rate of 750 tons per hour, or nearly

double the working rate of the “largest dredger in the world.” For the

hourly capacity for consecutive hours, something must be deducted for

time lost in going to dump or to change scows, and in the case of the

St. Lawrence dredgers this reduces the hourly rate to about 650 tons,

still, leaving them, however, better than the best rate of the Otago

dredger.

Average rates for a day, or longer periods, are further reduced, for

both kinds of dredgers, by detentions for shifting anchors, moving

out of the channel for passing vessels, and other contingencies, not

present in a mere trial of speed. The St. Lawrence dredgers, however,

often raise 4800 cubic yards in twelve hours, or an average of 500 tons

per hour, while, according to the published reports for a recent month,

two of them raised an aggregate of 117,525 cubic yards of clay, giving

an hourly average of 336 tons per dredge for 69 hours of duty per week.

As a combined steamship and dredger which can be turned out complete

on the Clyde for export, the Otago dredger is said to be the largest

and the best thing yet built, but as a machine to dig a channel, one of

these St. Lawrence dredgers is better still.[300]

Another comparatively modern machine is known as the La Châtre

dredger, 92 feet long, and 20 feet width of hull. It has an engine

of 50 H.P., which works the chain of buckets. The material falls 2⅔

feet from the buckets into a long steel shoot 2¼ feet in width and

depth, and semi-circular at the bottom, extending out 15⅓ feet from

the axis of the dredger, and supported by twenty-four steel cables

from shear-legs 80 feet high, standing on two iron pontoons fastened

to the dredger; a pontoon on the opposite side, weighted with 32 tons

of ballast, counterweights the shoot. The material is drawn along the

shoot (which has a general inclination of 1 in 20, increasing close

to the dredger) by water pumped into the shoot, at least double in

volume the amount of material. The dredger, shortly after starting

work, lifted and transported 183 cubic yards of excavation per hour.

It cost about 10,800_l._ Another dredger deposited the material

from the buckets on a divisor formed of two sets of revolving sharp

blades, turning in opposite directions, which cut up the large pieces

and discharge the material on gratings of sharp blades, through which

it falls, mixed with about 85 per cent. of water, on a sheet-iron

inclined plane, along which it is conveyed to the pipe of a suction

pump. This Dumont 1-foot pump, specially designed for silt, stands

with its engine on a pontoon alongside the dredger. Another similar

pump draws along the silt discharged by the first, and discharges it

into a 1-foot iron pipe. The silt is deposited from 650 to 1000 feet

away, at a height of 16 to 20 feet, with a velocity of about 13 feet

per second. The mound formed at the outlet of the pipe has a very

flat slope, but the settlement is rapid and complete. The dredger was

able at once to lift and transport 130 cubic yards per hour, and this

amount will probably be eventually raised to 160 cubic yards. This

dredger is said to have cost 12,800_l._, with its accessories.

In the construction of the Amsterdam Ship Canal, the excavations had

to be deposited on the banks some distance away from the dredgers;

and after being raised by the ordinary bucket dredger, instead of

being discharged into barges, they were led into a vertical chamber

on the top side of a sand-pump, suitable arrangements being made for

regulating the delivery. The pump known as Burt and Freeman’s was 3½

feet in diameter, and made about 230 revolutions per minute; it drew

up the water on the bottom side, and mixing with the descending mud

on the top side, the two were discharged into a pipe 15 inches in

diameter. The discharge-pipe was a special feature in this work, and

consisted of a series of wooden pipes jointed together with leathern

hinges, and floated on buoys from the dredger to the bank. In some

cases the pipe was 300 yards long, and discharged the material 8 feet

above the water-level. Each dredger and pump was capable of discharging

an average of 1500 cubic yards per day of twelve hours. A centrifugal

sand-pump, designed by Mr. Hutton, was also used on those works.

At Hull, the cost of dredging on the Humber, including everything

except interest on capital and depreciation, is stated to be 2·1_d._

per ton. The material is mud, varying in consistency, and it is

discharged about 1½ miles from the docks by steam hoppers, and by

ordinary mud-barges and tugs.

On the Clyde, the average cost, including everything—depreciation,

interest, and carrying in hopper barges 27 miles—is as follows:—Very

hard clay, boulders, and sand, 30·15_d._ per cubic yard; hard silt,

gravel, and sand, 24·17_d._; silt, clay and sand, 8·49_d._; silt,

gravel, sand, clay, and mud, 8·08_d._; and silt and sand, 7·94_d._ per

cubic yard.

On the Tyne, the cost varies from 2_d._ to 6½_d._ per ton, according to

the nature of the material. One dredger has dredged over 1,000,000 tons

in one year, and, including discharging a distance of 17 or 18 miles,

the cost per ton was a little over 3½_d._

The cost of removing the bar at Carlingford Lough, including

everything—Parliamentary expenses and insurance of plant—was about

1_s._ 9_d._ per ton. Taking the cost for one season, it was 1_s._ 4_d._

to 1_s._ 5_d._ per ton, or 2_s._ to 2_s._ 3_d._ per cubic yard. The

material was hard clay and boulders.

At Aberdeen, the cost of dredging and transporting about 2 miles beyond

the bar, including insurance, but not depreciation and interest, is

1_s._ 2_d._ per ton for dredging, and 2·9_d._ for discharging, giving a

total of 4_s._ 1_d._ per ton.

On the Wear, at Sunderland, the total cost of dredging, including every

item of depreciation and interest, is 2·37_d._ per ton. The material

consists of sand, gravel, and clay.

On the Tees, at Stockton and Middlesbrough, the cost of dredging sand,

gravel, and occasionally boulders, including the conveyance of deposits

out to sea, a distance of about 12 miles, is 4·96_d._ per cubic yard or

about 2½_d._ per ton. This amount includes everything except interest

on capital expended on dredging plant.

On the Birmingham Canal., when there has been any slipping of the

sides, or a discharge into it of water laden with silt and detritus

from cuttings and high lands, the material, if soft, costs 5_d._ to

9_d._ per ton to dredge; and if hard, from 10_d._ to 14_d._ per ton.

With a “spoon dredger” the cost is about 8_d._ per ton, and with a grab

dredger it is about 5_d._ where the circumstances are favourable.[301]

Where hard material has to be dealt with, the water is taken out of

the canal, and the material is excavated by pick and shovel. On narrow

canals dredging costs more, owing to the necessity of having a narrow

beam, to enable the dredger to enter the canal. The beam is, however,

sometimes increased when the machine is working by attaching baulks of

timber or iron pontoons to the sides, to prevent its capsizing.[302]

The dredging machines that were chiefly employed on the Danube

regulation works were, on an average, from 25 to 30 H.P., and

had one inclined arm, which could be depressed to work in a depth of

22 feet of water or more. They were high enough to load direct into

the waggons, by means either of a distributing table or an elevating

endless chain bucket. The dimensions of the machine, which was found to

be very economical, were:

ft. in.

Length of boat 88 7

Breadth ” 19 8

Height ” 7 9

Draught of water 3 11

The working steam pressure was six atmospheres, and the power consisted

of a vertical engine of 15¾ inches cylinders and 35-7/16 inches stroke;

the main shaft was 7-1/16 inches in diameter, and the ratio of the

pinion to the driving-wheel was 1 to 7. The buckets were of steel,

having a capacity of 8·75 cubic feet. The links of the chain were 31½

inches long, 1¾ inch by 3½ inches for those to which the buckets were

attached, and 15/16 inch by 3½ inches for the others. These machines

were employed in several different ways on the Danube works. They

load direct into waggons, running upon a side track, either by means

of a transporting apparatus or of an elevating wheel and buckets. The

transporting apparatus was attached to the dredge, and consisted of a

girder about 46 feet long, guiding and carrying an endless band formed

of steel plates mounted on chains, which were driven by wheels at each

end of the girder. The buckets of the dredging machine discharged their

contents upon this band, to which a forward motion was imparted by

an independent six-horse power engine, and the forward movement thus

given discharged the ballast in the waggons alongside. The whole of

this system rested at one end on the deck of the drag, and at the other

on trestles, secured in a small auxiliary boat fastened alongside the

machine. It was afterwards considered that a useful alteration might be

made in the means of transferring the ballast, and with this object a

large wheel, fitted with buckets, was mounted on the dredge, and

driven by an independent engine. The wheel was of wrought iron, 19

feet 8 inches in diameter, and furnished with buckets which received

the ballast from those of the dredging machine, and, after raising,

discharged it into an open channel, whence it fell into the waggons.

The buckets of this wheel were fixed to the periphery, and were so

arranged as to discharge automatically into the channel. It was found

that this mode of loading produced excellent results, but the full

capacity of the dredgers could not be developed, both on account of the

loss of time incurred, and because the material dredged was not always

easily transferred into the waggons. A large quantity of the material

excavated was also loaded into barges and taken by them to suitable

points of discharge.

The amount of work performed by the dredging machines depended greatly

on the means available of removing the earth excavated, and to do

this with regularity, and without loss of time, was one of the most

difficult portions of the work of excavation.

During 1870 and 1871 the dredging machines loaded almost exclusively

into the waggons by means of the endless bands already described. Two

of them were worked exclusively in this manner; other two began to load

into boats in 1872, and the following year this method was entirely

adopted with them, and their production was remarkably large. Another

machine loaded the waggons by means of the large wheel. The dredging

machines employed on the first and third sections of the works, and

which also loaded into boats, gave remarkable results.

The Condreux excavating machine consists essentially of a carriage

carried upon three lines of rails. A lateral projecting arm carries an

endless chain with buckets, passing around a wheel at the lower end of

the arm. This chain is driven by a 20 horse-power engine, mounted on

the frame of the carriage, and the whole machine is caused to traverse

on the rails by means of a small four-horse locomotive. The buckets,

which become filled in succession in traversing the face of the slope,

being excavated, are of steel plate or of wrought iron mounted with

steel edges. The buckets are mounted on two pitched chains, which, in

rising, pass over a loose pulley placed at the level of the road, and

serve as a support to the loaded buckets. This arrangement largely

reduces the friction, and prevents excessive torsion of the chain. The

loaded buckets are discharged automatically, by means of flap openings

in their bottoms, and their contents fall either into the waggons

alongside, or into inclined conducting channels. These machines run

alongside, and at the top of, the excavations they make, and the earth

which they raise can be either deposited alongside so as to form a

continuous embankment, or be loaded into waggons.

On the Mersey Dock Estate, which extends over a total water area of

520 acres, the dredgers used up to 1875 were of the ladder type, five

of them having double, and one single ladders. A double set of hopper

barges was attached to each dredger. The barges were 50 feet long by

20 feet beam, and contained 82 cubic yards. The expense of towing the

barges out to the Seacombe Narrows, where they deposited their silt,

rendered the operations costly, and in 1874 a steam hopper barge

was brought into use, 144 feet long, 23 feet beam, 11 feet 9 inches

depth of hold, and with a hopper capacity of 285 cubic yards. In

1876 two other hopper barges of the same size were brought into use.

Subsequently, larger barges, with a hopper capacity of 414 cubic yards,

were introduced. These have been found much more economical than the

old system.

FOOTNOTES:

[299] Paper on ‘Recent Improvements in the port of Dublin,’ read in

1878 before Section G of the British Association.

[300] Mr. Kennedy, chief engineer of Montreal, in _Engineering_,

September, 1881.

[301] Paper by Mr. G. R. Jebb on “The Maintenance of Canals,” &c., in

the ‘Journal of the Society of Arts’ for 1888.

[302] On the Birmingham Canal, which has an average top width of 36

feet, and an average depth of 5 feet, this has to be done with a

Priestman Grab Dredger, but it causes very little trouble.

CHAPTER XXXIV.

CANAL BOATS.

“Instructed ships shall sail to quick commerce,

By which remotest regions are allied;

Which makes one city of the universe,

Where some may gain, and all may be supplied.”

—_Dryden._

One of the most important matters that the canal engineer and manager

has to deal with, is the adoption of the form of boat best suited for

the gauge of his canal and the character of the traffic to be dealt

with. The majority of canals are of too limited dimensions to admit

of the employment of boats of large size. Even on some of the largest

rivers—such as the Thames, the Danube, and the Rhine—the size of

vessels employed has to be kept down to a limit which would be deemed

ridiculous for ocean-going steamers. This fact alone renders the cost

of transport on inland waterways much greater than the cost of sea

transport. There is also the great drawback to be met, that on many

through lines of communication, as on the through canal routes from

Birmingham to London, and from the same midland capital to the Severn,

the break of canal gauge renders it necessary to employ the size of

boat suited to the minimum gauge, and this is, of course, a great waste

of power.

The modified French canals of 6½ feet depth admit barges of 300 tons;

and a depth of 8½ feet, on the Canal du Centre, of Belgium, allows of

the passage of 400-ton barges. The large traffic on the Erie Canal,

between Lake Erie and the Hudson River, is conducted in barges of 250

tons; the canal has a depth of 7 feet, with a bottom width of 56 feet,

and pitched side slopes of 1 to 1·5; and the locks are 110 feet long

and 18 feet wide. The Welland and St. Lawrence Canals are on a larger

scale, as they provide access to the coast for the large inland lakes

of North America, with vessels of 1000 to 1500 tons, and therefore,

like the Ghent-Terneuzen Canal, occupy a sort of intermediate position

between inland and ship canals.

The “river steamer,” as the stern-wheel shallow draught vessels on

Canadian waters are called, is a boat of peculiar construction. Three

things are absolutely necessary. First, a perfectly smooth bottom;

second, an absence of rigidity in the hull and motive-power; third, a

propelling-power on the surface of the water—three points, apparently

easy of accomplishment, but in reality very difficult, and which to

understand requires long practice with the steamers, and their uses.

Indeed, no inconsiderable portion of a captain’s or pilot’s life

has passed before he has learned the “handling”; but when once the

lesson has been learned, it is wonderful what can be done with these

wheelbarrow steamers.

Mr. Shelford[303] holds that these are by far the most useful class of

boats employed on the canals of Canada. The absence of a keel or any

such obstruction enables the boat to be turned like a dish on the

water; while the four rudders (sometimes 20 feet long) will guide her

with a nicety in rapids and currents where an ordinary steamer would be

helpless. The absence of rigidity in the hull and machinery enables the

steamer to be driven ashore on any soft bank, the cargo discharged or

loaded, and the boat without difficulty backed off.

The propelling power is a large diameter wheel at the stern of the

boat, the full width of the vessel, resembling the undershot wheel of

a mill, and driven by two cylinders, one on either side. The floats

of this wheel are but 8 to 10 inches in the water when light, and 30

inches when loaded, and do not therefore produce those destructive

currents which come from the screw or paddle steamer.

The boats which are used on the rivers of the north-west of Canada are

about 220 feet, 38 to 40 feet beam, and 10 to 12 inches draught when

light, and carry themselves about 400 tons, and will push (not tow)

three times as much more on barges built like the steamers.

Perhaps the most efficient system of canal boats and of canal transport

generally known in the United Kingdom is that adopted on the Aire and

Calder Canal. Steamers are employed to tow a fleet of canal boats or

barges, varying from ten to twenty in number, each carrying about 40

nett tons of traffic. The locks, which are 215 feet in length, take

the steamer, tender, and eleven boats all at one time; but if there

is a longer train of boats, it has to be broken in two. The boats are

20 feet long, 16 feet wide, and 7 feet or 7 feet 6 inches deep. When

loaded, they draw from 6 feet to 6 feet 6 inches of water, and the

whole train carries from 700 to 900 tons. Usually, instead of towing

these boats, they are pushed from behind, which offers an advantage in

the steering. The steamer has two direct-acting cylinders—one on each

side, and a wire rope is carried round a pulley direct to them, being

afterwards threaded through guides attached to each boat. The steering

arrangements are so contrived that the train can go to any curve by the

two convex surfaces, and yet it is free to rise and fall vertically.

The boats are coupled together by wire ropes, which run alongside the

whole of the boats through guides at each corner of each boat. The

ropes are then passed over the steering wheel upon the steamer. The

boats are really iron boxes, which, when traffic is carried, say from

Leeds to Goole for shipment, are placed in a hoist, inside which there

is a cage with a cradle, in which the boat is secured. When the boat

has been raised to the height of the shoot it turns over automatically

and discharges the coal or other cargo into the ship through the

shoot or spout employed for that purpose. The boat and cradle, having

resumed their original position, are then lowered back again to the

canal-level by the same hydraulic arrangement employed to raise

them. Mr. Bartholomew, the Manager of the Aire and Calder Canal, has

stated[304] that the cost of mineral transport by this system, including

the return empties, was only 0·0119_d._ per ton per mile; the cost of

tugs carrying general cargo and merchandise being ·034_d._ per ton per

mile; whereas the cost of the same traffic on the Leeds and Liverpool

Canal, where similar facilities do not exist, would be ·30_d._ per ton

per mile. The difference of cost is mainly due to the difference in the

number of men employed. Usually, two men are employed on each boat,

and four men are employed for tugging, making 28 men in all for 12

boats, whereas a train of boats can be worked by the system described

by the tug crew of four men only. The Aire and Calder Company have

now arranged their boats in such a way that they may carry general

merchandise as well as minerals, having fitted them with decks and

hatchways for that purpose.

Mr. E. J. Lloyd submitted to the Select Committee on Canals (1889)

a statement showing the size of the craft that the various canals

of England and Wales were capable of carrying.[305] The figures are

instructive, and are worth perusal by any one interested in the

subject. It showed that there are very few cases in which the existing

navigations can carry craft over 100 feet in length. The most usual

dimensions are 70 or 75 feet by 12 or 14 feet width. The Aire and

Calder Canal, which takes boats of 212 feet by 22 feet, is a notable

exception to the general rule. Boats of 163 feet by 29 feet 6 inches

can also travel on the Gloucester and Birmingham Navigation, while the

Severn can take craft of 270 feet by 35 feet, and the Thames, from

London Bridge, can carry vessels of 140 feet by 22 feet. Again, on part

of the Kennett and Avon Canal, craft of 120 feet by 18 feet can be

navigated. Mr. Lloyd, who has had a great deal of experience in canal

navigation, has proposed the adoption of improved locks on the leading

English canals capable of taking boats 110 feet long, 11½ feet wide,

and 6 feet draught, the carrying capacity being about 120 tons.[306]

Mr. Abernethy has proposed that the canal boats should be capable of

carrying 200 tons, and the canals adapted thereto;[307] while Sir James

Allport has contended that for facility of handling traffic small boats

are better than large ones, and should be preferred accordingly.[308]

In India, steamers have been placed by Government on the Sone canals,

and will continue to run until the task is taken up by private

enterprise, as is now being done on the Orissa canals.

The following is a description of one of them named the _Koel_:—

Length 114 feet

Beam over all 16½ ”

Draught, full loads 3½ ”

Coal bunker capacity 7 tons

Of which 5¾ tons are used on the trip between the head of the canal and

Arrah and back, being a run of 116 miles, occupying about 26 hours, or

at the rate of 7·450 lbs. per hour, a very large consumption for an

engine of 25 nominal H.P.

Accommodation is provided for 8 first-class passengers and 150

second-class passengers, with a cargo capacity of 2500 cubic feet, or

50 tons of 50 cubic feet.

The engine of 25 H.P. was one of the locomotives used on the

Quarry Tramways. The pressure of the steam is 120 lbs. The vessel is

built with a single paddle-wheel, 11½ feet diameter, at the stern with

20 floats, 5 feet long by 1 foot broad.

The hull of the boat is 3/16ths iron, perfectly flat-bottomed and

rectangular in section, with rectangular bilge. The bow is curved, with

a vertical stern, and the stern is sloped off for 24 feet to a vertical

depth of 1 foot, for the purpose of enabling the backwater to escape

when the wheel is reversed. There are two rudders, and the steering is

managed from the fore part of the boat. Her speed is between 6·5 and 7

miles an hour in the canal, but the run of 58 miles occupies from 11 to

12 hours down stream, and 13½ to 15 hours up stream, owing to the delay

in passing the locks, of which there are six.

These steamers last year carried 42,900 passengers and 2500 tons of

goods, earning 3175_l._

The cost of working the different steamers, inclusive of all charges

but that of interest and depreciation, amounted to from 9·36_d._ to

36·48_d._ per mile run.

The total earnings of the canal for the past year was 7080_l._, against

9300_l._ in 1881-82.

The tolls levied on boats are from ⅛_d._ to 1/5_d._ per ton per mile.

The charges by the steamer amount to about ⅜_d._ per ton and per

passenger per mile. The charge by native boats varies with the demand,

and is high. The bulk of the traffic is carried in native boats, which

are worked by men. The sections of the two main canals in the Sone

system are very large. They have to provide for the irrigation of

1,295,000 acres. They are about 200 feet broad, with a depth of 9 feet

in full supply, diminishing to about 7 at the minimum. The branches

vary from 90 to 60 feet at surface, with a minimum depth of 6 feet.

The time occupied by a boat in passing through a lock comprises the

entrance and exit of the boat, and the operations in locking. By the

adoption of sluices in the side walls the locks on the Bourgogne Canal

can be filled or emptied in two minutes; but the time employed in

taking in and bringing out a boat varies considerably, depending on the

speed of the boat, its draught, and its method of traction. Steamboats,

carrying from 100 to 150 tons of merchandise, traverse a lock in from

six to eight minutes, whilst yachts and torpedo-boats have passed in

four to six minutes. The main water traffic between Paris and Lyons is

carried on by new boats 125 feet long, and having a draught of 4½ feet,

being limited by deficiency in the depth of the Yonne. These boats can

carry 210 tons, but their load is usually between 130 and 180 tons;

they perform the journey between Paris and Lyons in 11 to 12 days,

traversing the Bourgogne Canal in six or seven days.

Boatbuilders often err in constructing boats of the largest size that

the locks will admit, thus rendering the entrance and exit of the boats

both slow and troublesome. A boat of 200 tons, travelling 22 miles per

day, is more serviceable than a boat of 275 tons which can only go 12½

miles. The greater speed entails a somewhat greater cost in traction;

but it admits of more voyages, the transport of more freight, and a

more regular service. The lengthening of the locks on the Burgoyne

Canal, by enabling the tonnage to be increased by one-third, without

diminishing the speed of transit, or notably increasing the cost of

traction, has proved a profitable work for the inland-navigation

commerce of France.

In 1871, the Legislature of the State of New York, with a view to

enabling the Erie and other canals under their jurisdiction to be more

profitably utilised, passed an Act to foster and develop the internal

commerce of the State, by inviting and rewarding the practicable

and profitable introduction, upon the canals, of steam, caloric,

electricity, or any motor, other than animal power, for the propulsion

of boats.

The first section of this Act appointed a commission to practically

“test and examine inventions, or any or all devices, which may

be submitted to them for that purpose, by which steam, caloric,

electricity, or any other motor than animal power, may be practically

and profitably used and applied in the propulsion of boats upon

the canals; said examination and tests shall be had by the said

commissioners at such time or times during the season of canal

navigation, for the year 1871-72, as they may order and direct;

said commissioners shall have the right, and they are hereby

expressly required, to reject all such inventions or devices, if, in

their opinion, none of the said inventions or devices shall fully

and satisfactorily meet the requirements of this Act; but said

commissioners shall demand and require,

1. The invention or devices to be tested and tried

at their own proper costs and charges of the parties

offering the same for trial.

2. That the boat shall, in addition to the weight

of the machinery and fuel reasonably necessary for the

propulsion of said boat, be enabled to transport, and

shall actually transport, on the Erie Canal, on a test

or trial exhibition, under the rules and regulations

now governing the boats navigating the canals, at

least 200 tons of cargo.

3. That the rate of speed made by said boat shall

not be less than an average of three miles per hour

without injury to the canals or their structures.

4. That the boat can be readily stopped or backed

by the use and power of its own machinery.

5. That the simplicity, economy, and durability

of the invention, or device, must be elements of its

worth and usefulness.

6. That the invention, device, or improvement can

be readily adapted to the present canal boats; and,

“Lastly, that the commissioners shall be fully

satisfied that the invention or device will lessen

the cost of canal transportation, and increase the

capacity of canals by any means of propulsion or

towage, other than by a direct application of power

upon the boat, which does not interfere in any manner

with the present method of towage on the canals, and

complying in all other respects with the provisions of

this Act, may be entitled to the benefits thereof.”

The system known as the Belgian system, or any mode of

propulsion by steam engines or otherwise, upon either

bank of the canal, was, however, excluded. A number of

attempts have been made to meet these desiderata, of

which the system known as Baxter’s is, perhaps, the

most successful.

On the running canals of China, Sir George Stainton observed a boat

of light construction, with only 14 tons lading, of 8 feet width of

floor, about 10 feet width of water-line, and 50 feet of extreme

length, drawing 2 feet 3 inches of water, and sharp at the ends,

dragged against a stream whose velocity was 5½ English miles per hour;

and, although there were twenty-eight trackers, or men hauling at the

line, fastened to the boat, besides three men in the boat, poling

it on, it advanced only at the rate of a quarter of a mile an hour,

notwithstanding that the channel was not materially contracted, in

either width or depth of waterway, in proportion to the section of the

boat.

Many suggestions have been made, and not a few experiments carried out,

with a view to enabling canal boats to navigate waters covered with

ice—the use of canals in cold countries being usually limited, from

this cause, to about one-half of the year only. None of them appear,

however, to have been very successful.

About the year 1796, the Chevalier Bentancourt Molina presented to the

Society of Arts a model of a barge, having a windlass in its stern,

which gave a circular motion to a pair of knives or scythes, or a lever

giving an alternating motion to knives, for mowing off weeds close to

the bottom of a canal in which the barge is to float, or on the sloping

sides of the canal; for which purpose the knives could be made to

revolve at any depth below the surface of the water, and either

horizontally or inclined at any angle. In most winters it happens that

an ice not more than 1 or 1½ inches thick continues for a considerable

length of time on canals and other stagnant waters. This, or even a

less thickness of ice, is sufficient to stop the trade upon the canals

unless the ice is broken; and for this purpose it is advisable, every

morning of a frost, unless the ice should be found more than usually

thick, and the frost increasing and likely to continue, to break the

ice. This was in some cases done by a strong and square-headed barge,

whose sloping or projecting head was covered with strong iron plates.

One of these barges, being drawn along the canal and into each lock by

several horses, has a tendency to rise upon the ice, and thereby breaks

it down before the boat. About the lock-gates it was necessary to break

the ice by stamping with the end of a pole. Mr. Symington provided the

head of his steam-barge with stampers, to be worked by the engine, for

breaking the ice before it in frosty weather.

The tempting prospects of towing a train of ten 100-ton barges with

scarcely any more power than would be required to tow only one of them,

and the alluring advantages of speedily loading each separate barge,

and of detaching and attaching barges at intermediate wharves along

the canal’s course, were held out in a proposal recently discussed in

France for adopting single-width canals.