HARBOURS AND RIVERS.
1811-1843.
There is scarcely a harbour or river in Scotland about which, at some
time, Mr. Stevenson was not asked to give his advice. His opinion was
also sought in England and Ireland, and he executed works of greater or
less extent in many of the cases in which he was consulted.
We may select from his reports the names of Dundee, Aberdeen,
Peterhead, Stonehaven, Granton, Fraserburgh, Ardrossan, Port-Patrick;
the rivers Forth, Tay, Severn, Mersey, Dee, Ribble, Wear, Tees, and
Erne, as among some of the many places in the United Kingdom where he
was employed.
In a subsequent chapter extracts will be found illustrating Mr.
Stevenson’s views on various professional subjects, and from these
it will be seen that he brought his large experience and study of
the waves to bear advantageously and practically on his harbour
engineering. He was, as will be gathered from the extracts, at an early
period fully alive to the value of spending basins for tranquillising
a harbour, and of the proper disposition of the covering piers, in
reference to the line of exposure, so as to avoid throwing sea into
the harbour’s mouth, or causing it to heap up on coming in contact
with the piers; while, as regards rivers, he was no less alive to
the value of _backwater_ in keeping open estuaries, and to the
necessity of removing all obstructions to the free flow of the tide in
river-navigation.
At an early date, for example, Mr. Stevenson and Mr. Price were jointly
consulted as to the navigation of the Tees, and I am indebted to Mr.
John Fowler of Stockton, the engineer to the Tees Navigation, for the
following statement as to the result of that joint reference:--
“The Navigation Company consulted Mr. Stevenson and Mr. H. Price, who
differed in opinion as to the general treatment of the river. Mr. Price
recommended that it should be contracted by jetties, and Mr. Stevenson
that the banks should be faced with continuous walls, stating as his
reason for this recommendation, that ‘to project numerous jetties into
the river, I regard as inexpedient, being a dangerous encumbrance
to navigation, and tending to disturb the currents and destroy the
uniformity of the bottom.’ The plan adopted by the Navigation Company
was, however, that of Mr. Price; and jetties were constructed on the
river to a large extent,” and Mr. Fowler adds, that “after a trial
of twenty-seven years it was found that they were liable to all the
objections that had been urged against them by Mr. Stevenson.”
Accordingly, under Mr. Fowler’s direction, the whole of the jetties
have been removed.
One of the early harbour schemes in which my father was engaged in
England, was a harbour at Wallasey Pool, on the Mersey, in which he
acted in conjunction with Telford and Nimmo. The following reports
will show the nature and extent of work then contemplated as a
commencement of the Birkenhead Docks, now so valuable an adjunct to the
port of Liverpool. But at the early period of 1828, when the reports
were written, the public were not prepared to entertain a scheme of
improvement based on so great a scale. It included, as will be seen,
not only the formation of a floating harbour at Wallasey on the
Mersey, but the construction of a harbour at Helbre on the Dee, with a
connecting ship canal between the two estuaries.
“_To the Subscribers for the proposed Wet Docks at Wallasey Pool._
“PRELIMINARY REPORT of ROBERT STEVENSON and ALEXANDER NIMMO, Civil
Engineers, on the proposed improvements at Wallasey Pool.
“_Liverpool, Feby. 23, 1828._--Having been requested to examine
the situation of the Wallasey Pool with a view to discover how far
additional accommodation might be obtained there for the increasing
trade of the port of Liverpool, we did accordingly meet at Woodside on
the 10th February 1828, and after examining the pool at high and low
water, and the action of the tides on the northern edge of the Leasowe
level, which we found to be overflowed at high water of the 16th and
17th and 18th February, with off-shore winds and moderate weather,
we next examined the shore down to low water in that place called
Mockbeggar Wharf, which we found to consist of turf and soft marl over
a bottom of fine clay. We afterwards visited the western part of the
level, which extends to the immediate vicinity of the estuary of the
Dee, part of which we examined, also Helbre, Hoylake, and the Rock
Channels, and directed certain surveys and levels to be taken for our
further information, and though we have not yet obtained all the data
requisite for forming estimates of the expense of improvement, we are
generally of opinion as follows:--
“That this situation of Wallasey Pool affords, beyond doubt, the most
favourable position in the vicinity of Liverpool for an extension of
the accommodation of the shipping trade of the port, at a very moderate
expense.
“The ground being level, the soil water-tight and of easy excavation,
docks may be formed there of any extent. The bay in front between
Seacombe and Woodside, though mostly shallow at present, affords the
first place of shelter within the Mersey, and small vessels lie there
out of the stream in perfect safety. It possesses a creek or channel
which could easily be enlarged and deepened so as to form an outer
tide harbour similar to the original harbour of Liverpool, but upon a
greater scale, and for the scouring of which it would be easy to open
up the tide in the pool to the extent of 250 acres, as far as Viners
Embankment, and above that to any extent that may be thought desirable.
This space having a deep creek through its whole extent forms a
complete half-tide basin for facilitating the entrance into the Docks
on either side, while on the shallow parts may be formed extensive
timber-ponds. Works of masonry in this situation being out of the
sea-way and of the stream of the tide, may be constructed with great
economy; good building stones are to be found at Bidston Hill, and the
whole soil is a brick earth.
“The situation possesses other advantages of access not so obvious,
but which may eventually be of the greatest importance. The Leasowe
level at the head of this pool extends as far as the river Dee, and
touches the sea-shore at Mock Beacon, where indeed it is occasionally
overflowed by the tide. In this direction it would be quite practicable
to open a direct passage for ships into the Horse Channel, by
excavating in marl and clay, only quite clear of the shifting sands
which are found in all other parts of the Mersey and Dee. And towards
the Dee a ship canal may easily be cut with its entrance either at
Dawpool in Hoylake, or in a tide harbour which could be formed at
Helbre, a position which affords many maritime advantages.
“That position has several good anchorages in its vicinity, three
different passages to sea, and is only five miles from the floating
light, the distance of which from Liverpool by Wallasey and Helbre is
exactly the same as by the Rock Channel; and nine miles of it would be
inland navigation, instead of an intricate passage among sandbanks, the
whole of which inland navigation is an addition to the floating harbour.
“Having thus briefly shown the facilities possessed to seaward, we may
next turn our attention to those connected with the inland navigation.
It is evident that to the ‘flats’ which navigate the Duke’s Canal,
Mersey and Irwell, Ellesmere, Sankey, and Weaver Navigations, Wallasey
Pool is just as accessible as the Docks of Liverpool, while by a canal
to Helbre you communicate with the large navigation of the Dee, and the
valuable mineral county of Flintshire; and if ever, as is extremely
probable, the canal navigation should be brought nearer to Liverpool,
the natural termination would be Tranmere or Wallasey Pool, between
which a cut can be easily formed. By this means boats from the small
canals in Staffordshire and the other inland counties can be brought
down to the seaport and return their cargo without the trouble of
transhipment,--an object, as being important to the proprietors of
these canals, that there can be little doubt of their endeavouring to
carry it into effect whenever the shipping can be accommodated on the
Cheshire side.
“Although in the present state of our survey, and until we meet our
eminent friend and colleague Mr. Telford, we are not prepared to
enter into any detail of plans or estimates of the expense of these
improvements, yet we are satisfied he will agree with us in opinion
that the cost of even the most expensive will be greatly inferior to
that of obtaining any important additional accommodation upon the
Liverpool shore, which being almost entirely occupied already, we
consider it impossible to obtain there at any expense sufficient room
for the increasing trade; and we would conclude this preliminary report
by recommending to the thriving and enlightened community of Liverpool
to weigh well the advantages above alluded to, and the benefit of now
extending their operations to the Cheshire shore.
“ROBERT STEVENSON.
ALEXANDER NIMMO.”
“INTENDED SHIP CANAL between the RIVERS DEE and MERSEY.
“THE REPORT of THOMAS TELFORD, ROBERT STEVENSON, and ALEXANDER
NIMMO, Civil Engineers, recommending Two extensive new Sea
Ports, etc., on the Rivers Dee and Mersey, adjacent to
Liverpool, with a Floating Harbour or Ship Canal to connect
them.
“The undersigned, having so far completed their land and water surveys
as to enable them to speak with confidence upon the practicability of
extending the accommodation for shipping to suit the rising demands
of this great commercial emporium, beg leave to commence their report
upon this important subject by describing the general outline of the
proposed improvements, and then to proceed to discuss them in detail;
but previous to this it is necessary to make a few preliminary remarks.
“_On the Estuaries of the Dee and Mersey._
“In one or other of these must always continue to be the great port of
the north-west of England, the preservation and improvement of which
has become the more important since this last century has added so
much to the progress of manufacturing and commercial enterprise, and to
that extension of inland navigation, which has rendered Liverpool not
only the great mart of the north-west of Britain and of all Ireland,
but nearly of the whole western world.
“The chief feature of these estuaries is the extensive range of
sandbanks in their front, through which an intricate ship-navigation
has to be carried. These channels have been always subject to
variations, and are now only safely navigated by a careful system of
pilotage.
“In the progress of our investigations, and feeling the great
importance of the measures we are about to recommend, we have carefully
inquired into the various changes which have taken place on these
banks, as far as can be collected from history or inferred from
observation, in order to be enabled to judge what is likely to take
place as to their future permanent condition.
“In the time of the Romans the Ribble seems to have been the chief port
of this district, and Ribchester is said to have been a city as great
as any out of Rome; the port was Poulton below Preston, at the Neb of
the Naze, so vastly inferior at the present time to various situations
on the Mersey and the Dee that it is impossible not to admit that some
extraordinary change has taken place in their physical condition since
that period. Tradition says that the port of the Ribble was destroyed
by an earthquake, and also that there were tremendous inundations in
Cheshire and Lancashire about the termination of the Roman sway in
Britain; and various phenomena we have seen seem to point to some such
catastrophe.
“It is well known that in the Saxon times the river Dee was an
important navigation, and that Chester was then and for many ages after
the great port of the west, and for the connection with Ireland, whilst
the Mersey was little known, and Liverpool only a fishing village.
“But in after times the port of Chester was so much obstructed by
sandbanks in the upper portions that the city became inaccessible to
vessels of large draught, and though serious efforts were made to
remedy this evil, and have even partly accomplished it, yet the trade
of the country was gradually transferred to Liverpool on the Mersey,
which had become a place of considerable importance at the time of the
Revolution, and had been created an independent port: before, it was
only a creek of Chester.
“In our inquiries into the early state of the navigations of the Dee
and Mersey, the oldest chart we have found of any authority is that of
Grenville Collins, in 1690. It is dedicated to King William, to whom he
acted as pilot on his expedition to Ireland; and as that army embarked
from Hoylake, as also that of the year before under General Schomberg,
and as Collins was officially employed in making charts of the coast,
there can be no doubt that, though rude, it conveys, as far as it goes,
an authentic representation of the state of navigation at that time.
“The roadstead of Hoylake was then spacious and deep, with five fathoms
into it, and seven fathoms inside, from one half to three quarters of a
mile wide, and covered by the Hoyle Sand, which was then one solid bank
without any swash or opening across it, and was dry at neap tides as
far as opposite the Point of Air and beyond.
“The Dove Point then projected a mile and three-quarters from the
shore, separating Hoylake from the Rock Channel, which was then nearly
dry at low water as far as Mockbeggar, between which and Burbo Sand
there was only one quarter fathom, and between Dove Point and Burbo
only two fathoms.
“The large vessels which at that time belonged to Liverpool put out
part of their lading in Hoylake until they were light enough to sail
over the flats to Liverpool.
“The union of Hoylake and the Rock Channel formed, as at present,
the principal passage to sea, called the Horse Channel, then a fair
opening with three to seven fathoms, but considerably to the eastward
of the present channel of that name; for Collins’s sailing mark through
it was Mockbeggar Hall upon the Banquetting-House in Bidston, would
mark the present Spencer’s Gut as having been the channel. The north
spit did not then exist, or rather was part of the Hoyle bank; and the
Beggar’s Patch seems to have been the extremity of Dove Point. The
Formby Channel was said to have three fathoms on the bar, but was not
buoyed or beaconed, therefore not used.
“The Chester bar had nine feet least water; and Wild Road is marked
as good anchorage, much used in the coal trade. About 1760, published
in 1776, we have the Survey of Mackenzie, who was employed by the
Admiralty to make charts of the western coasts of Britain, which are
still in high reputation.
“At this time Hoylake continued to be a good roadstead, though greatly
altered; the depth at entrance was only two fathoms, eight fathoms
in the middle, the width only three furlongs, and its length had
diminished at least a mile. A passage was opened from the Rock Channel
across to Dove Point into Hoylake, and across the east end of Hoyle
Sand, with four to eight fathoms, forming the present Horse Channel.
“On this chart we also perceive the beginning of another opening across
the Hoyle Sand, now called Helbre Swash, then dry at low water at each
end, having three fathoms in the middle, now a deep and fair channel
with seven to nine fathoms, and two and a half least water at its mouth.
“Since the opening of this channel or swash little or no tide sets
through the Hoylake, which is gradually closing up, and now used only
for small craft.
“The existence of Hoylake was of material importance to Liverpool and
also to the Dee, for vessels could run there at any time; the entrance
to it was marked by leading lights in the middle of last century, one
of the first applications of reflecting lights to the purposes of
navigation; they are now of little use, as the sand has shifted to the
eastward, and the entrance is nearly dry at low water.
“The Rock Channel seems to have undergone a very important change by
the time of Mackenzie’s survey. We have observed that in Collins’s
time, 1690, it was dry at low water as far nearly as Mockbeggar.
Although this is still nearly the case at the Perch at low tides, it is
opened below that in a material degree. In the space of seventy years
the channel had deepened to have three or four fathoms in Wallasey
Hole; also between Mockbeggar Wharf and the north bank, which was dry
at low water; and a channel had opened across Dove Point, with two and
three fathoms, into Hoylake, and from thence across the east end of
Hoyle, forming the present Horse Channel, as before described, with
four to eight fathoms out to sea. On the other hand, the sand from
this deepening had been carried down to seaward, forming a complete
shoal across the original Horse Channel of Collins’s time, in whose
sailing-line is marked a depth of four feet only, and this shoal
connected with that called the Beggar’s Patch, and thence with the spit
or flat along the west side of the Horse Channel, on which was six
feet water. This last channel was direct and fair, with five to eight
fathoms, and previous to the publication of Mackenzie’s chart, but
after the time of his survey, was marked by two lighthouses at Leasowe
shore, and subsequently by that on Bidston Hill under the direction of
Captain Hutchinson, as was also the entrance into Hoylake by the two
lights near Meols, as before described.
“The Formby Channel is marked as deep upon Mackenzie’s chart, with
four fathoms at the entrance, and between Taylor’s Bank and Middle
Patch two fathoms; there is now only five feet over the flats at low
water at its entrance, and it was buoyed in at Mackenzie’s time; but,
though the deepest channel to Liverpool, it is, from its intricacy and
instability, still very little used for navigation.
“Lieutenant Evans published a survey of the Liverpool and Chester
rivers, with a book of sailing directions, which is in good repute. We
have preferred the chart by Mr. Thomas in 1813, made by order of the
Lords of the Admiralty, for the purpose of comparison with the several
before mentioned surveys, as more minute in detail.
“At the time of this survey, fifty years after that of Mackenzie,
Hoylake had diminished in breadth to one furlong; the depth at the
entrance was three to seven feet; four fathoms near the Red Stones;
since that time it is still shallowing, and now may be walked across at
low water, from Dove Point to East Hoyle; so that this roadstead may be
considered as lost.
“Helbre Swash had opened to half a mile wide, with six or eight fathoms
water, but with a shoal at its entrance of one fathom; there are now
two fathoms and a half through that entrance.
“The Brazil or North Bank had extended dry, at low water, as far as
Spencer’s Gut Buoy, and the North Spit or four feet flats had extended
into the Horse Channel across the line of sea lights, thereby forcing
that channel further into Hoyle Bank. The lower part of the Rock
Channel had enlarged by the formation of a passage on each side of the
Beggar’s Patch.
“The entrance to Formby Channel had very much altered since Mackenzie’s
time, and, though better marked, still continued to be little
frequented. The floating light placed opposite Helbre Swash and the
Horse Channel, outside of all the banks, has made a great improvement
in the access from the seaward in that direction.
“The Rock Channel, from these circumstances, continues to be the main
passage to and from the harbour of Liverpool, but it is only provided
with day marks, and though well buoyed cannot be navigated by night;
being very narrow, and having banks in its middle, it is difficult for
vessels to beat through with foul winds in one tide, and as there is no
secure anchorage, frequent delays and losses take place in this part of
the navigation.
“Within the harbour of Liverpool or in the river Mersey the principal
places of anchorage are--
“1st, Abreast the town.
“2d, Off the Magazines, which is used by the outward-bound vessels.
“3d, Up the river in Sloyne Roads, or Broombro Pool, which is almost
confined to vessels under quarantine.
“In the two first-mentioned anchorages a great sea tumbles in, with NE.
gales, and this, with the rapid tide and bad holding ground, causes
vessels to drift, even with two anchors down, so that it is necessary
for all the merchant vessels, as soon as the tide serves, to proceed
into dock and remain there until a favourable opportunity occurs of
putting to sea, so as to get through the Rock and Horse Channels with
daylight; hence a considerable accumulation of vessels within the docks
at all times, but especially when there has been a continuance of
northerly and westerly winds, and which has made it necessary to look
now for additional accommodation on the opposite shore of Wallasey Pool.
“_Proposed establishment at Wallasey._
“Small craft find good shelter on the banks at the mouth of Wallasey
Pool, being there out of the stream, and land-locked by the Point of
Seacombe.
“The steamers also, to which dispatch is of moment, moor along this
shore, and if there was more room in Wallasey Pool it would decidedly
be the best anchorage about Liverpool.
“Wallasey Creek runs nearly for two miles from the Mersey, where it
is stopped by an embankment, through which the waters of 3000 acres
of marsh land pass by a tunnel. The pool below the embankment covers
nearly 250 acres at spring-tides, and by its backwater maintains a
channel through the creek down to low water springs, and with seventeen
feet at high water springs as far up as the embankment.
“Previous to the embankment it is certain that this creek was
materially deeper. On Mackenzie’s chart, opposite to its mouth, there
are twenty fathoms marked, being much more than anywhere within the
Mersey at present, and a bottom of rock. This channel would therefore
be restored by any considerable addition to the backwater; and at
all events, if the lower parts of the creek were opened by dredging,
and, by a power of scouring it, low water obtained, a safer inlet for
vessels to run to would be acquired than at present exists anywhere in
the neighbourhood of Liverpool.
“On the south side of the creek, between Woodside Ferry and Bridge End,
there is a bottom of sandstone rock, but this ceases at Bridge End
Creek; and above that place the shore is composed of firm clay, fit for
brick making, to a depth at least of thirty feet, in which excavation
for docks and basins could be carried on with great facility.
“Upon the attention being directed to Wallasey Pool as a commercial
station, it will appear at first view obvious that an entrance might
be made along the low ground which extends from it to the sea shore
at Leasowe, by which a direct passage to sea might be obtained, and
the insecurities and dangers of the bar and banks of the Rock Channel
be avoided; but the objections to such an entrance are, that the
channel outside affords no safe anchorage, and the cut would be exposed
directly to the stroke of the sea, and if protected by piers their
construction would not only be expensive, but might also materially
alter the channel along shore.
“But the ground continues equally favourable to the westward as far as
Hoylake and the Dee below the hill of the Grange. The shore is skirted
by a narrow belt of sandhills, through which however there would be
no great difficulty in making a passage into the tideway. Here it
is important to remark that the Helbre Swash opens a deep and fair
channel, well sheltered by banks on each side, and only five miles in
extent to the floating light, which is in a direct line with it.
“This channel has been formed within the last century, and readily
accounts for the deterioration of Hoylake; it now carries down most
of the ebb of the Dee, and is likely to improve still more, having
deepened materially since Thomas’s survey in 1813.
“Through all the vicissitudes we have traced there has been deep water
and good anchorage at the point of Helbre Island; and as that situation
affords solid rock for every sort of construction, there can be no risk
of the permanency of any work that may be established there.
“Sea-locks constructed at Helbre would be protected against the
prevailing westerly gales by the island itself, against the northerly
by the bank of East Hoyle; and they may be connected to the mainland by
banks formed across the strand, which is mostly dry at high water of
neap tides; and by means of these banks a pond of sixty-four acres may
be enclosed, which, being filled at spring tides, may be employed for
the purposes of scouring and keeping open the harbour and its entrance,
and as a reservoir for a ship canal from thence to the shore, and along
the low ground to Wallasey Pool. Such a canal, of large dimensions, and
seven miles long, will be one continued floating harbour, which may be
carried to a great extent in various directions and on the same level.
“Independent of Helbre Swash two other channels for ships passing
to sea unite at that position; one, the original Hoylake, still
sufficiently navigable at high water; the other, the passage by Wild
Road and Chester Bar, greatly superior in safety and permanency to that
of the Formby Channel; for in all the successive charts little or no
change seems to have taken place on that bar, which continues to have
nine feet at low water, with a rise of thirty. The great extent of
ebb-tide from the Dee (being quite as extensive an estuary as that of
the Mersey) must always keep one or other of those channels or all of
them open, so that ships may sail from Helbre in almost every wind; and
if necessary to beat out, a vessel starting from Helbre with the first
of the ebb down the Swash will be at the floating light and clear of
the banks before another from Liverpool can get round the Rock Perch.
“To persons at all acquainted with the navigation to Liverpool it
must be quite unnecessary to point out the benefit of this proposed
arrangement, which, while it preserves all the advantages of
communicating with the Mersey, and the extensive inland navigations
connected therewith, affords a new passage to and from the sea,
by means of the Dee, by which both the distance and dangers of an
intricate navigation will be wholly avoided.
“An important advantage obtained by this plan is, that the proposed
entrance at Helbre is within the jurisdiction of the port of Chester,
of which it is recorded as a creek in Sir Matthew Hale’s Treatise _De
portibus maris_; and business done there or upon its waters, even as
far as Wallasey Pool, being within the port of Chester, will have to
pay the dues at that port; and unless ships and goods lock into the
Mersey they are exempted from the dues of Liverpool. The facility of
construction is so great that a moderate charge for dues will be a
sufficient remuneration for the capital required. The ground on either
side of the canal is singularly suitable to be appropriated to any kind
of establishment connected with shipping, and there can be no doubt
that it will be so employed even by private speculation; but in so
extensive a scheme as we propose it will be advisable for the promoters
of the measure at once to establish a set of docks and warehouses
of the most perfect description, as has been done in all the docks
which have been constructed in and adjacent to London, and we have
accordingly designed a set of such warehouses and yards as part of the
plan.
“_Details of the Plan._
“Commencing at the river Mersey, we propose to dredge out and widen
Wallasey Creek at least to the depth of three feet under low water of
spring tides, being four feet below the sill of Prince’s Dock, and
this for 200 feet in width up as far as the entrance into the basins;
to lay the sill of the greater entrance lock at that level, also the
sill of the basin of the barge lock. The barge entrance lock to have
a lift of ten feet; the ship lock four feet; so as to give the same
water when the gates are opened as into the Prince’s Dock. The side of
Wallasey Creek will be quayed for four hundred yards below the entrance
of the dock, to facilitate transporting vessels into and out of the
basins.
“The tide basin is 1000 yards long, and 100 yards wide in the middle,
curving on the north side towards the locks at each end, the south side
receding 100 feet, so as to give berthage to timber vessels, and in
the front of them a sloping wharf and bonding yards for timber; a line
of barge canal between these yards and the warehouses on the main dock
will facilitate the removal of the timber without interfering with the
shipping.
“The entrance lock into this basin from the tideway will be fifty feet
wide, the entrance wing walls widening gradually to 100 feet, to afford
easy access to the shipping when both gates are thrown open. At low
water, neaps, or half tide, two or three vessels may pass at a time.
The upper lock between this basin and the canal to be double; one large
lock, forty-five feet wide and 160 feet long, for great ships, and
another, twenty-five feet wide, for smaller vessels, with gates at each
end, pointing both to land and seawards. These locks to rise to four
feet below the old dock sill of Liverpool, and thus to have twenty-two
feet water in the canal on the level of an eighteen feet tide, which we
propose to make the surface level of the canal.
“The ship dock parallel to this basin will be 400 yards long and 100
wide, with warehouses on each side, supported by iron pillars, so as to
form a covered wharf, as at the St. Katherine’s Dock in London; behind
these warehouses a parallel barge canal fit for river flats, forty feet
wide, which will, as in Holland, be found a singular convenience.
These canals communicate with a dock and basin for flats only, whence
the barges may be let down into the creek during the ebb; and as they
navigate at the lowest water they will be ready to pass up the Mersey
with the first of the flood; and in like manner, coming down with the
last of the ebb, will get into the pool and enter the dock without
losing a tide. Ships from the Mersey, in like manner, may enter the
basin with half-flood, and be ready to proceed down the Swash with the
first of the ebb.
“The flat marsh by the Boilers Yards is well adapted for this
establishment, but as the ground beyond is high for some distance we
propose the canal to be 124 feet only at water surface for 1000 yards
from the locks, and to be lined with a stone wall on each side, so that
this space will, in fact, be also a dock. Afterwards the marsh widens,
and here is a favourable place for another entrance basin and dock,
if necessary. From this point we propose to continue the canal with
sloping banks, the bottom to be four feet under the level of the old
dock sill, and 163 feet in width at the surface of the water, which
will be twenty-two feet in depth.
“The canal proceeds at first in the direction of the Leasowe
Lighthouse, and approaches within half a mile of the shore, and about
the same distance north of the village of Moreton, and then turns to
the westward, keeping half a mile inland from the villages of Great and
Little Meols through Newton Car, where it turns off to Helbre Island,
and enters the strand about half a mile above the hotel; across the
strand it is carried by embankments to the upper end of Helbre Island.
A large breadth is allowed for the embankment on the sea-side, with
facing mound of stone from the rocky point near the Red Stone to within
600 feet of the Point of Helbre. The head of this pier to be of rough
stone, rounded off, and carefully paved. A pier head is to be built
in Helbre of 300 feet in length, leaving an opening of 300 feet into
the tide harbour, which is fifty acres in extent, and to be cleared
to at least low water of a spring-tide, and preserved of that depth by
scouring.
“A quay wall is to be constructed of hewn stone along the Helbre Island
from the pier-head 600 yards to the tide lock, which is to be fifty
feet wide, as at Wallasey; another tide lock of similar dimensions on
the north side of the harbour. The north pier is only intended to be
of rough stone; but a short covering pier will be made to protect that
lock and facilitate the entry of ships. Above these locks the canal is
to be formed into a tide basin of 500 yards in length, the level of
which may be kept at that of the tide of the day; and at the upper end
are two parallel canal locks, as at Wallasey, with gates pointing to
the sea and land at each end, as the tide will occasionally rise higher
than the level of the water in the canal.
“From Helbre Island to the Middle Helbre, thence to the Eye, and from
that to the shore at Kirby Church, an embankment and road will be
carried along the ridge and made water-tight. By this and the canal a
pond, as has already been described, will be enclosed, of 640 acres,
which will fill at spring-tides to the depth of nine feet, containing
3,000,000 of cubic yards, and may be all emptied for the purpose of
scouring the outer harbour; but at the latter part of the spring tides
it will be advisable to fill this pond as a reservoir for lockage
water, for which purpose it may be drawn down three feet to the canal
level, and will hold 1200 locks-full for ship lockage at each end,
and, if necessary, 1000 more locks-full may be drawn off without any
material inconvenience to the navigation.
“We now subjoin an estimate of what we conceive will be the expense of
completing these works, including an extensive range of warehouses on
each side of the dock at Wallasey Pool, and of enclosed timber yards
along the tide basin; and for all the items we have made a liberal
provision.
“_Estimate._
Excavations in Wallasey Creek and Helbre Harbour, also in
the Locks, Basins, and Canal to Helbre, and Barge Canal
and Basins, £436,017
Quay Walls on Creek, Basins, Locks, and Canal at Wallasey
Pool, 230,100
Bridges and Tunnels, 38,000
Piers and Quays Walls, Helbre Harbour, 95,100
Locks, Dams, and Culverts, Helbre Harbour, 111,000
Warehouses at Wallasey Pool, Inclosure Walls, and Paving, 183,000
Purchase of Land, 125,000
For Surveys, Act of Parliament, Law Expenses,
Superintendents’, Lock-keepers’, and other Offices,
etc., and Contingencies on Works, Fifteen per Cent., 182,731
----------
£1,400,948
==========
“For the above sum a floating harbour will be obtained of seven miles
in length, capable of indefinite enlargement, with extensive warehouse
accommodation, and with a sea-port at either end on the two separate
estuaries. That this is not too great for the wants of the country will
be at once admitted by those who consider the vast extent of shipping
usually moored in the Thames, notwithstanding all its docks; the total
inapplicability of the rivers Mersey or Dee to such a purpose; and the
confined space which even the docks of Liverpool can afford for the
accommodation of a trade now hardly inferior to that of the metropolis,
and certainly and rapidly increasing.
“THOS. TELFORD.
ROBT. STEVENSON.
ALEXANDER NIMMO.
“LONDON, _16th May 1828_.”
“FURTHER REPORT respecting the proposed two new Ports, etc., on the
Rivers Dee and Mersey, adjacent to Liverpool.
“In the foregoing report we have shown the form and expense of this
establishment when completed upon an extensive and perfect plan.
At the commencement, however, of so great an undertaking it is
not to be expected that all the conveniences we have proposed can
be immediately required; a considerable portion may therefore be
deferred until the wants and increasing demands of trade shall show
them to be necessary. In the meantime the essential parts of the
improvement may be effected, with a smaller expenditure of capital,
so as to obtain all that safety and facility of access which we
have shown to be leading features of this plan.
“We have proposed to make the canal from Wallasey to Helbre wide
enough for three great ships, so as to admit of part of it being
used as a floating harbour, still leaving room for navigation;
but for navigation alone it will be quite enough to adopt the
dimensions of the Caledonian Canal, viz., 120 feet at surface,
and if the trade should increase so as to require it, instead of
widening it, a parallel canal may hereafter be made, with a bank
and two towing-paths between, leaving the whole of the opposite
banks applicable to berthage and commercial establishments. The
same locks will serve at either end, and the transporting of ships
be greatly facilitated; and the construction of this canal, or
repair of the other, may be effected without any interruption to
the navigation by such an arrangement. Again, the double locks at
the Wallasey end of the canal, intended for the greater dispatch
of business, may very well be deferred for the present, and the
entrance basin made of smaller dimensions. The ship dock there may
at first be made as a part of the canal, and quayed on one side
only, and afterwards widened and completed when wanted. The half
tide dock may be dispensed with by enlarging the barge tide dock so
as to serve also for ships, and the quay walling of the pool and of
the first mile of the canal may also be deferred. The warehouses at
Wallasey dock may be dispensed with at first, or left to individual
capital; but it will be highly proper to secure a sufficient
quantity of land to enable all these improvements to be undertaken
at some future period. We do not deem it advisable to give up the
enlargement and deepening of the entrance of Wallasey Pool, as on
that depends much of the utility of the plan in giving access to
vessels at low tides; and for a similar reason we would preserve
all the works proposed for the harbour at Helbre Island. Upon this
modified plan the expense, as below, will be £734,163.
“THOS. TELFORD.
ROBT. STEVENSON.
ALEX. NIMMO.
“CHESTER, _July 14, 1828_.
“_Estimate._
Excavating Tide Basin, Barge Dock, and half of Ship Dock,
at Wallasey End, £25,000
Walling along the Pool, from Brassey’s Works, also the
Barge Dock and one side of Ship Dock, 31,500
Ship Lock, Barge Lock, and Tide Gates for Basin, and two
Swivel Bridges, 36,500
Dredging Wallasey Creek, as before, 20,000
Land and Damages, 51,000
-------
£164,000
Fifteen per Cent. Contingencies, 24,485
-------
For Wallasey End, £188,485
=======
Excavating Canal, £207,403
Bridges and Tunnel, 22,000
Land and Damages, 27,000
-------
£256,403
Fifteen per Cent., 38,460
-------
For the Canal, £294,863
=======
Pier and Quay Walls from Helbre, as before, £95,100
Locks, Dams, and Culverts, do., 111,000
Excavation in Harbour, 10,000
Strand and Damages on Isle, 2,000
Fifteen per Cent., 32,715
-------
£250,815
-------
GENERAL TOTAL, £734,163”
=======
I have given the Reports of the three Engineers to whom this question
was remitted, to show the very comprehensive view they took of the
important subject referred for their opinion; and it is almost
unnecessary to tell professional readers that after a lapse of nearly
a quarter of a century the embryo but comprehensive proposal of
Telford, Stevenson, and Nimmo resulted in the modified but still large
Birkenhead Dock scheme of J. M. Rendel.
* * * * *
The original design for the improvement of the Tay was made by Messrs.
Robert and Alan Stevenson, in 1833, and in connection with my father’s
life a short account of the works may be desirable as illustrating his
practice in River Engineering in the Tay and other rivers.
The river Tay, with its numerous tributaries, receives the drainage
water of a district of Scotland amounting to 2283 square miles, as
measured on Arrowsmith’s map. Its _mean_ discharge has been ascertained
to be 274,000 cubic feet, or 7645 tons of water per minute. It is
navigable as far as Perth, which is twenty-two miles from Dundee and
thirty-two from the German Ocean.
Before the commencement of the works, certain ridges, called “fords,”
stretched across the bed of the river, at different points between
Perth and Newburgh, and obstructed the passage to such a degree that
vessels drawing from ten to eleven feet could not, during the highest
tides, make their way up to Perth without great difficulty. The depth
of water on these fords varied from one foot nine inches to two feet
six inches at low, and eleven feet nine inches to fourteen feet at
high water of spring tides; so that the regulating navigable depth,
under the most favourable circumstances, could not be reckoned at
more than eleven feet. The chief disadvantage experienced by vessels
in the unimproved state of the river was the risk of their being
detained by grounding, or being otherwise obstructed at these defective
places, so as to lose the tide at Perth,--a misfortune which, at times
when the tides were falling from springs to neaps, often led to the
necessity either of lightening the vessel, or of detaining her till the
succeeding springs afforded sufficient depth for passing the fords.
The great object aimed at, therefore, was to remove every cause of
detention, and facilitate the propagation of the tidal wave in the
upper part of the river, so that inward-bound vessels might take the
first of the flood to enable them to reach Perth in one tide. Nor was
it, indeed, less important to remove every obstacle that might prevent
outward-bound vessels from reaching Newburgh, and the more open and
deep parts of the navigation before low water of the tide with which
they left Perth.
The works undertaken by the Harbour Commissioners of Perth for the
purpose of remedying the evils alluded to, and which extended over six
working seasons, may be briefly described as follows:--
_1st_, The fords, and many intermediate shallows, were deepened by
steam dredging; and the system of harrowing was employed in some of
the softer banks in the lower part of the river. Many large detached
boulders and “fishing cairns,” which obstructed the passage of vessels,
were also removed.
_2d_, Three subsidiary channels, or offshoots from the main stream, at
Sleepless, Darry, and Balhepburn islands, were shut up by embankments
formed of the produce of the dredging, so as to confine the whole of
the water to the navigable channel, and the banks of the navigable
channel were widened to receive the additional quantity of water which
they had to discharge.
_3d_, In some places the banks on either side of the river beyond low
water mark, where much contracted, were excavated, in order to equalise
the currents, by allowing sufficient space for the free passage of
the water; and this was more especially done on the shores opposite
Sleepless and Darry islands, where the shutting up of the secondary
channels rendered it more necessary.
The benefit to the navigation in consequence of the completion of
these works was of a twofold kind; for not only was the depth of
water materially increased by actual deepening of the waterway, and
the removal of numerous obstructions from the bed of the river, but a
clearer and a freer passage was made for the flow of the tide, which
begins to rise at Perth much sooner than before; and as the time of
high water is unaltered, the advantages of increased depth due to the
presence of the tide is proportionally increased throughout the whole
range of the navigation; or, in other words, the _duration of tidal
influence has been prolonged_.
The depths at the shallowest places were pretty nearly equalised,
being five feet at low and fifteen feet at high water, of ordinary
spring tides, instead, as formerly, of one foot nine inches at low and
eleven feet at high water. Steamers of small draught of water can now
therefore ply at _low water_, and vessels drawing fourteen feet can now
come up to Perth in _one tide_ with ease and safety.