association with the China trade, constructing a long series of
successful steamers for the Holt company and for other lines, with
services from Britain to the Far East, and carried out very extensive
work in the building up of the coasting trade of Asia and Oceania.
For the Holt line alone there have been constructed by the Scotts
forty-eight steamers, aggregating 148,353 tons; while the propelling
machinery of these represents 19,500 nominal horse-power. For the India
and China services there have, in the past fifty years, been completed
over one hundred and thirty steamers.
The China Navigation Company, Limited, was formed in 1873 by Messrs.
John Swire and Sons, of London, for trading in China, and the first
steamers built for them by the Scotts were two vessels of 1200 tons
gross, completed in 1876.
Since then the Scotts' yard has practically never been without a vessel
for one or other branch of the Eastern trade, and particularly for
the China Navigation Company, which runs steamers from China as far
south as Australia, as far west as the Straits, and as far north as
Vladivostock and the Amur river. They also have ships trading up the
Yangtsze Kiang to Ichang, 1000 miles from the sea, where the rapids
prevent navigation farther into the interior. For this service the
twin-screw steamer was adopted in 1878, much earlier than in many other
trades, largely owing to the strong advocacy of the late John Scott,
C.B. Up to that time most of the Yangtsze steamers were propelled
by paddle-wheels driven by walking-beam engines. The first of the
twin-screw steamers was built in 1878--a vessel of 3051 tons gross--and
there has been constructed since then a long succession of very
serviceable steamers. For this line alone, sixty-four vessels have been
constructed by the Scotts, the aggregate tonnage being 115,600 tons,
while the nominal horse-power of the propelling machinery fitted to
these vessels is 15,000 horse-power.
[Illustration: Plate XIII. THE "ACHILLES" OF 1865 OFF GRAVESEND.]
But having in our brief historical sketch come to times within the
recollection of the reader, it may be more satisfactory to depart from
the purely chronological review of the company's operations, and to
offer rather an analysis of the progress made, deferring a description
of typical modern steamers for a separate Chapter.
The direct-acting vertical engine, with inverted cylinders, almost
as we know it to-day, and as illustrated in connection with the
work of the twentieth century, was introduced in the late 'fifties.
The compound engine, introduced in 1854, was developed into the
triple-expansion system in 1882, and later into the quadruple-expansion
type; but this latter has not been much adopted, only some 3 per cent.
of the vessels registered at Lloyds being so fitted. This is in a large
measure due to the satisfactory economy attained with triple-expansion
engines. As to the progress made, Table II., giving average results at
different periods, is instructive.[51]
TABLE II.--PROGRESS IN THE ECONOMY OF THE MARINE ENGINE, 1872 TO 1901.
-------------------------------------------+-----+-----+------+------
|1872.|1881.|1890. | 1901.
-------------------------------------------+-----+-----+------+------
Boiler pressure in pounds per square inch |52.4 |77.4 |158.5 | 197
Coal consumption in pounds per indicated | | | |
horse-power per hour | 2.11| 1.83| 1.52 | 1.48
Consumption on prolonged sea voyages in | | | |
pounds per indicated horse-power per hour |... | 2 | 1.75 | 1.55
Piston speed in feet per minute |376 |467 |529 | 654
-------------------------------------------+-----+-----+------+------
The advance of the century may be popularly expressed by stating that,
whereas in the first coasting steamships built by the Scotts the fuel
consumed in carrying 1 ton of cargo for 100 miles was 224 lb., the
expenditure to-day is from 4 lb. to 5 lb. The economy of the steam
engine has accounted, as is shown in the Table, for a considerable part
of this improvement. But, at the same time, the growth in the size of
ships has enabled the normal speed of 10 knots to be realised, with an
addition to engine power of much less ratio than the increase in the
capacity of the steamer. As to speed, recent progress has been most
marked in the Navy, and it is therefore fitting that here we should
direct our attention to Naval work.
[Illustration: decoration]
[Illustration: Plate XIV. MODEL OF H.M.S. "PRINCE OF WALES," 1803.]
FOOTNOTES:
[17] Woodcroft's "Steam Navigation," page 20, etc.
[18] Woodcroft's "Steam Navigation," page 54.
[19] Deas' "Treatise on the Improvements and Progress of Trade on the
River Clyde" (1873), page 24.
[20] Muirhead's "Life of Watt," pages 428 and 429.
[21] Williamson's "Clyde Passenger Steamers," pages 348 to 351.
[22] James Napier's "Life of Robert Napier," page 21.
[23] This was the second of the name--a favourite one after the Duke
of Wellington's great victory, and gave rise to the following poetic
effusion:--
And now amid the reign of peace,
Art's guiding stream we ply;
That makes our wheels, like whirling reels,
O'er yielding water fly.
As our heroes drove their foes that strove
Against the bonnets blue;
On every side the waves divide
Before the _Waterloo_.
--Millar's "Clyde from Source to Sea," page 179.
[24] Millar in "Lecture on Naval Architecture and Marine Engineering at
Glasgow Exhibition, 1880-81," page 138.
[25] "Greenock Advertiser," August 6th, 1819.
[26] "Steamboat Companion" for 1820.
[27] Millar, "On the Rise and Progress of Steam Navigation." Lectures
at the Glasgow Exhibition (1880-81), page 138.
[28] Hodder's "Life of Sir George Burns, Bart.," page 161.
[29] Williamson's "Clyde Passenger Steamers," page 32.
[30] Lindsay's "History of Merchant Shipping," vol. iii., pages 78 to
80.
[31] Weir's "History of Greenock," page 89.
[32] Williamson's "Memorials of James Watt" (1856) page 228.
[33] "Greenock Advertiser," July 5th, 1839.
[34] "Greenock Advertiser," February 5th and May 25th, 1835.
[35] Fincham's "History of Naval Architecture," page 294.
[36] Sir Thomas Sutherland, in the "Pocket Book of the P. and O.
Company" (1890), page 15.
[37] Fincham's "History of Naval Architecture," page 235.
[38] Sir John Ross's "Steam Communication to India by the Cape of Good
Hope" (1838), page 31.
[39] "Greenock Advertiser," January 22nd, 1839.
[40] Fincham's "History of Naval Architecture," pages 320 and 321.
[41] Lindsay's "Merchant Shipping," vol. iv., page 86.
[42] "Practical Mechanic's Journal," vol. i., 1853.
[43] The number of steam vessels belonging to the United Kingdom
in 1849 was only 1142, of 158,729 tons; Sweden, which was second
among the nations of the world, had only about one-tenth of this
tonnage.--Porter's "Progress of the Nation," page 626.
[44] Holmes' "Marine Engineering," page 74.
[45] Rankine's "Steam Engine," page 502.
[46] "Transactions of the Institution of Naval Architects," vol.
xxviii., page 141; and vol. xxx., page 278.
[47] Lindsay's "Merchant Shipping," vol. iv., page 434.
[48] "Proceedings of the Institution of Naval Architects," vol. xi.,
page 152.
[49] Lindsay's "Merchant Shipping," vol. iv., page 435.
[50] Pollock's "Modern Shipbuilding, and the Men Engaged in it," page
199.
[51] "Proceedings of the Institution of Mechanical Engineers" (1901),
page 608.
[Illustration: decoration]
A Century's Work for the Navy.
[Illustration: decoration]
The work for the Navy by the Scotts began with the building, in 1803,
of a sloop-of-war named _The Prince of Wales_; a photograph from the
model of this vessel is reproduced on Plate XIV. Since the construction
of this ship the firm have carried out several important Admiralty
contracts, including the first machinery manufactured in Scotland for
a dockyard-built ship, the first steam frigate built in the North, and
several later ships, with their engines; the most recent order being
for the machinery of the armoured cruiser _Defence_, of 14,600 tons
displacement, and 27,000 indicated horse-power, to give a speed of 23
knots.
The progress demonstrated by a contrast between the small sloop-of-war
and this latest powerfully-armed and well-protected high-speed cruiser,
is a record of research and invention, not only on the part of the
naval architect, but also of the chemist, the metallurgist, and the
engineer; the triumph is greater than that reviewed in the case of the
Merchant Marine. Great speed has been achieved, notwithstanding that
the problems to be solved in its attainment have been intensified by
the limitations in the size of the ship in order to minimise the target
presented to the enemy's fire, and by the necessity of providing for
heavy armour, armament, and ammunition in the displacement weight.
When a comparison is made of the Navy ships at the beginning of the
nineteenth century with those of a hundred years earlier, it is found
that little progress had been made, either in design or in gun-power.
The largest vessel in 1700 was of 1809 tons burden, with a hundred
guns. A century later, the size had increased only to 2600 tons, with a
hundred and twenty guns.[52] But even this was an exceptionally large
vessel. The British ships were, as a rule, smaller, and perhaps slower,
than the French ships; but then--as now and always--skill in strategy,
courage in combat, and devotion to duty were the most powerful
factors in action. No fault in these respects could be found with the
work of our Navy in the various engagements which terminated in the
epoch-marking victory in Trafalgar Bay.
The peace following the Napoleonic wars was not conducive to
advancement, as there was little incentive to pursue the sciences
which contributed to the development of destructive weapons. Steam as
a motive power and iron as a constructive material were not so readily
adopted in the Navy ship as in the Merchant Marine. Progress in the
utilisation of iron was not continuous. The first application of steam
was belated, and its popularity was not unalloyed.
[Illustration: Plate XV. _From an Old Engraving._ THE LAUNCH OF THE
FIRST CLYDE-BUILT STEAM FRIGATE "GREENOCK," 1849.]
The Admiralty ordered their first ship of iron in 1839--a small,
non-fighting boat for the Dover station--and there followed other
vessels for the exploration of the River Niger. But the first
iron fighting ship was not built until 1843. In 1848-9 the Scotts
constructed the iron steam frigate _Greenock_, the largest iron warship
of her day, and the first steam frigate built on the Clyde. The
over-all length of this vessel was 213 ft., the beam 37 ft. 4 in.,
and the depth of hold 23 ft. She was of 1413 tons burden, and carried
ten 32-pounder smooth-bore muzzle-loading guns. The illustration on
Plate XV. is a reproduction from an old engraving of the launch of the
vessel. It is a noteworthy feature that the figure-head was a bust
of John Scott, the second of that name. This compliment by the Naval
authorities of the time was well merited, as he did much not only for
the advance of naval architecture, but also for the development of
Greenock.
As a writer of the day put it, this vessel was the _experimentum
crucis_ of the principle of constructing fighting ships of iron.[53] By
1850 there were six large iron vessels, ranging downwards from the 1980
tons of the eighteen-gun ship _Simoon_, with eleven smaller vessels;
but they were all condemned, because it was found by experiment[54]
that the 32-pounder gun at short range could perforate the side of the
iron ship, and that the projectile carried its "cloud of langrage" with
great velocity into the interior of the ship, so that men could not
stand against it. Tests were also made with sixteen wrought-iron plates
superposed, to give a total thickness of 6 in., but these also were
perforated by the 32-pounder projectiles at 400 yards range; so that
the adoption of iron on the main structure of the ship was practically
delayed until armour-plates were first rolled in 1859.
The obstacle to the adoption of steam was the unsuitability of
paddle-wheel machinery for fighting ships. The wheel was exposed to
gun-fire, and the whole of the machinery could not be located below
the water line. Moreover, the side wheel limited the number of guns
which could be utilised for broadside fire. The first steam craft
ordered by the Admiralty was a small vessel of 210 tons and 80 nominal
horse-power, built in London in 1820.[55] Several other non-fighting
steamships followed. By 1837, the largest steam vessel in the fleet
was a sloop of 1111 tons and 320 horse-power.[56] In 1839 five steam
vessels were built, and two of them--the _Hecate_ and _Hecla_--were
engined by the Scotts. These wooden steamers were the first Naval
vessels sent to Scotland to have their machinery fitted on board. They
were of 817 tons and 250 horse-power. The paddle-wheels had a diameter
of 25 ft. 1/2 in., and there were seventeen floats. The main engines,
illustrated on page 29, represent the type adopted, not only in the
Naval, but in the Merchant service of this time. The steam pressure was
then about 3 lb. per square inch.
On Plate XVI. we illustrate the general arrangement of the machinery in
the _Hecate_ and _Hecla_. There were four boilers of the rectangular
type, each with two wet-bottomed furnaces at one end and large return
flues at the other end. The uptakes passed up inside the boilers
through the steam space, uniting in one funnel.
Smith's screw-propeller was tried experimentally in 1837, and
Ericsson's about the same time. The comparative trials of the
_Archimedes_ fitted with Smith's screw against existing paddle-steamers
did much to prove the efficiency of the new system.[57] The screw-ship
excelled the performance of paddle-steamers on the service, and the
screw-propeller was adopted by the Admiralty in 1845; twin-screws
followed twenty-five years later.
[Illustration: Plate XVI. MACHINERY OF H.M.SS. "HECLA" AND "HECATE,"
1839.]
The _Greenock_, built in 1848, was the first war vessel by the Scotts
fitted with the screw-propeller. We have already referred to her
construction in iron, and to her launch. She had a displacement of
1835 tons, and her engines were of 719 indicated horse-power. The
speed realised on the trial was 9.6 knots. The _Greenock's_ machinery,
which is illustrated on the next page, is specially interesting, as it
represents one of the earliest attempts to drive the screw-propeller by
gearing. Two horizontal cylinders were fitted, each 71 in. in diameter,
with a stroke of piston of 4 ft. The gearing consisted of four sets
of massive spur-wheels and pinions, in the ratio of 2.35 to 1, so
that 42 revolutions per minute of the engines give 98.7 revolutions
to the propeller-shaft. The propeller was 14 ft. in diameter, and was
so fitted that it could be detached and raised to the deck. There
were four rectangular brass-tube boilers, each with four wet-bottomed
furnaces, and all the internal uptakes united in one funnel, which was
telescopic, so that when it was lowered and the propeller raised out of
the water, the vessel had the appearance, as well as the facility, of a
sailing frigate.
As will be seen from the drawings, both the engines and boilers were
arranged very low in the hull, to be safe from the enemy's fire. The
engine and boiler compartment occupied 72 ft. of the length of the
ship--about one-third of the total length--and the seating for the
machinery was specially constructed, with a very close pitch of frames
which were only 1 ft. apart. For comparison with the drawings of the
machinery in the _Greenock_, we give on page 49 a similar drawing of
the machinery of the _Canopus_, of 12,956 tons displacement, seven
times that of the _Greenock_. To double the speed, the power of
machinery had to be multiplied twenty times, and yet the space occupied
is only about trebled.
[Illustration: MACHINERY OF H.M.S. "GREENOCK," 1848.]
[Illustration: MACHINERY OF H.M.S. "CANOPUS," 1900.]
In 1850 the largest of the steam vessels in the Navy[58] had a
displacement of 3090 tons, but the most noted was the _Dauntless_, of
2350 tons displacement, with engines of 1347 indicated horse-power
to give a speed of 10 knots. It is true that there were three smaller
vessels of greater speed, one of 196 tons steaming 11.9 knots; but this
was the highest rate reached in the Navy service. By this time some of
the fast mail steamers made 13-1/2 knots. These latter were suited for
war service, but we have already dealt with them.
Following the adoption of the screw-propeller in warships came the
abandonment of gearing for the engines. For many years various forms
of horizontal engine were used; first with return-connecting rods,
and subsequently with direct-acting rods. Steam pressures steadily
increased, largely owing to stronger materials being available. It was,
however, not until the 'seventies that the cylindrical boiler, the
compound engine, and the surface condenser admitted of an increase to
60 lb. per square inch[59]--several years after these improvements had
been introduced in the Merchant Marine.
The Scotts had worked steadily at the solution of the problem from
their trials with the _Thetis_ in 1858 (see page 34 _ante_). In 1860
the late John Scott, C.B., laid before the Admiralty a system of
water-tube boilers and compound engines, but objection was raised to
the system. The French Naval authorities, with whom the Scotts then
had close business connection, took up the scheme, largely because
of the favour with which it was viewed by M. Dupuy de Lôme, the head
of the Department. The first ship fitted was a corvette of 650 tons
displacement; the boilers worked at a pressure of 140 lb., while the
initial pressure at the compound three-cylinder engines was 120 lb.
These were the first engines of the compound type in the French Navy.
[Illustration: Plate XVII. _From a Photograph by Symonds and Co.,
Portsmouth._ H.M.S. "THRUSH," 1889.]
The Scotts were at the time building engines for four corvettes
under construction at the Woolwich and Deptford yards for the
British Navy; and the Admiralty agreed to have fitted in one of them
water-tube boilers and engines similar to those built for the French
boats. The boilers may be said to have belonged to the same general
type as the Thornycroft and Normand water-tube steam generators. It
was subsequently found impossible, however, to ensure that the top of
the boilers should be at least 1 ft. under the load-line--a condition
then enforced in steam vessels for the Navy--and the adoption of the
water-tube boiler was deferred, the ordinary machinery of the period
being fitted to work at 25-lb. pressure instead of 120-lb.[60]
This was unfortunate, as it removed the incentive to continued research
needed to make the water-tube boiler a really satisfactory steam
generator. The Scotts, however, continued to work for the successful
application of high pressures, and it was this that brought them into
contact with the late Mr. Samson Fox, with whom they were closely
identified for many years in connection with the development of the
corrugated flue and the cylindrical steam boiler.
Opinion being adverse to the water-tube boiler, notwithstanding its
acceptance by many foreign Navies, there was a strong agitation
fostered by engineers to induce the societies for the registry of
shipping, and also the Board of Trade, to increase the ratio of the
working to the test, pressure in boilers. The British Admiralty allowed
the boiler to be worked up to within 90 lb. of the test pressure,
whereas in the Merchant Service the working pressure was limited to
one-half of the test pressure. In 1888 the Scotts, being convinced that
the Admiralty system afforded quite a satisfactory factor of safety,
undertook the experiment of submitting a warship boiler, then being
built by them to Admiralty specification, to the highest possible
pressure, even up to bursting-point. The boiler ultimately leaked
to such an extent, after the pressure had been maintained for a
long period at 620 lb. per square inch, that it was not considered
necessary to proceed further. The stresses at this stage worked out to
48,130 lb. per square inch; and the result proved that there was some
justification for a reduction in the minimum scantlings of the shells
of marine boilers to, at least, the scale adopted by the Admiralty.[61]
These suggestive experiments were carried out in connection with the
boilers constructed in 1888-9 for two war vessels built by the Scotts.
These vessels were the _Sparrow_ and the _Thrush_. At the same time,
the Scotts engined two other vessels of the same type, constructed at
the Royal Dockyards. A view is given on Plate XVII. of the _Thrush_,
which was commanded by H.R.H. the Prince of Wales on the North American
and West Indian stations in 1891. She was a vessel of composite build,
of 805 tons displacement, with machinery of 1200 horse-power, to give a
speed of 13 knots; but, as is shown by the illustration, she was fitted
as a three-masted schooner, and utilised her sails when the wind was
favourable. In this respect, she marks the transition stage between the
days of the sailing craft and the modern ship, depending entirely on
steam for propulsion. Indication is afforded of the progress towards
this transformation by Table III. on the opposite page, which shows the
improvement in economy in the machinery of warships at various stages
in their development.
[Illustration: Plate XVIII. ENGINES OF H.M.S. "THRUSH," 1889.]
The figures in the Table are average results rather than highest
attainments during the periods. For 1890-95 we have taken the
_Barfleur_, the engines of which were constructed by the Scotts in
1894; whilst the particulars for 1895-1900 refer to the _Canopus_,
engined by them in 1900. In 1902 they also supplied the machinery
for the battleship _Prince of Wales_, and commenced the construction
of the armoured cruiser _Argyll_. But before referring in detail to
these latter ships, we may briefly review the advances in applied
mechanics, metallurgy and chemistry, which have contributed largely to
the perfection of these modern fighting ships in respect of offensive
and defensive qualities.
TABLE III.
PROGRESSIVE TYPES OF WARSHIP MACHINERY, AND THEIR ECONOMY, 1840 TO 1905.
------------------------+-------------+-------------+--------------
|1840 to 1855.|1855 to 1875.|1875 to 1890.
| | |
------------------------+-------------+-------------+--------------
Type of boiler | Rectangular | Rectangular | Single-ended
| box | box | cylindrical
| | |
Steam pressure per | 3 lb. | 25 lb. | 90 lb.
square inch | to 4 lb | |
| | |
Coal consumption per | 7 lb. | 4 lb. | 2-1/2 lb.
indicated horse-power | | to 5 lb. |
per hour | | |
| | |
Type of engine | Geared | Simple | Three-
| screw | horizontal | cylinder
| | surface | compound
| | condensing |
| | |
Piston speed in feet | 220 | 500 to 600 | 750
per minute | | |
| | |
Weight of machinery per | 10 cwt. | 3 cwt. | 3 cwt.
indicated horse-power | | to 5 cwt. |
per minute | | |
| | |
Speed of ship | 8 to 9 | 14 | 16
| knots | knots | knots
------------------------+-------------+-------------+--------------
------------------------+-------------+-------------+--------------
|1890 to 1895. |1895 to 1900.|1900 to 1905.
| [A] | [B] | [C]
------------------------+--------------+-------------+-------------
Type of boiler | Single-ended | Belleville | Water-tube
| cylindrical | water-tube |
| | |
Steam pressure per | 155 lb. | 300 lb. | 300 lb.
square inch | | |
| | |
Coal consumption per | 2 lb. | 1.8 lb. | 1.8 lb.
indicated horse-power | | |
per hour | | |
| | |
Type of engine | Three- | Three- | Four-
| cylinder | cylinder | cylinder
| triple- | triple- | triple-
| expansion | expansion | expansion
| | |
Piston speed in feet | 840 | 918 | 1000
per minute | | |
| | |
Weight of machinery per | 2-3/4 cwt. | 2 cwt. | 1.6 cwt.
indicated horse-power | | |
per minute | | |
| | |
Speed of ship | 18 | 18.25 | 23
| knots | knots | knots
------------------------+--------------+-------------+-------------
[A] Battleship, _Barfleur_.
[B] Battleship, _Canopus_.
[C] Armoured Cruiser.