Chapter VIII: Experimental Iron Shipbuilding

The suitability of iron for shipbuilding purposes had been admitted long before the construction of wooden vessels reached its limit as a profitable undertaking. The first experiments with iron were on a small scale, but they demonstrated the theory of displacement, so that observant marine builders had it borne in upon them that flotation depended rather upon the displacement of the floating body than upon the specific gravity of the material for which the floating body was constructed. But the general public was unconvinced, and making deductions from a limited knowledge of the subject, cried: “Put a piece of iron on the water and see if it will float.” With the increase in the size of wooden steamers and sailing vessels there came the demand for stronger, heavier, and thicker timbers for all parts. This meant so much more unremunerative weight of hull to be carried and so much less space available in proportion to the size of the vessel; so that in time the limit of carrying cargo at a profit and of staunchness of construction was bound to be reached.

In wooden steam-ships the limit of length was about 275 feet over all; the _Great Eastern_, built in 1858, proved that there was apparently no limit to the length of the iron ship.[78]

[78] Mr. John Ward’s Presidential Address to the Institution of
Engineers and Shipbuilders in Scotland, 1907.

This length has been exceeded by a few American wooden sailing vessels. The largest square-rigged vessel ever built in America, the shipentine _Shenandoah_, was of wood; her dimensions being 299·7 feet, beam 49·1 feet, and depth 19·9 feet; 3407 tons gross and 3154 net. She was built at Bath (Maine) in 1890 for Messrs. A. Sewall and Co., and was acquired a couple of years ago by the United States Government for a hulk at San Francisco, but has since been recommissioned. Though not a clipper in the strict sense of the word, she was a fast sailer and is sometimes called the last of the Yankee wooden clippers.

As wooden hulls were made larger they displayed a tendency, especially when they were built to carry propelling engines, to sag or hog, that is to say, to droop amidships or at the ends. This difficulty was ingeniously overcome in America, where wooden steamers were built longer and lighter and shallower than in Great Britain to suit the vast rivers of that country, by Stevens, who introduced his hogging frame, to which fuller reference has been made in Chapter II. But in the steamers of Great Britain, which were entirely for deep sea, this arrangement was impossible, and the solution of the difficulty had to be found in the use of a material other than wood.

The only substitute was iron. The change from wood to iron meant a saving in weight of hull of about thirty to forty per cent., while it is asserted that in a few cases there has been an even greater difference. The saving also meant that the difference in weight could be added to the weight of the cargo, without increasing the displacement; while another advantage was that the beams and ribs and stringers were of smaller dimensions, and the space thus gained, added to that obtained by the substitution of thin iron plates for wooden planking several inches thick, also very considerably increased the space available for the stowage of cargo. Practically every part of a ship was of wood until 1810, in which year the scarcity of oak resulting from the extensive felling of trees in the English forests compelled the use of iron for the knees or connections between the deck-houses and the ribs, and for the breast-hooks and pillars of ships.

An experimental iron barge was made in 1787 by J. Wilkinson the ironmaster.

As early as 1809 it was proposed by Richard Trevithick and Robert Dickenson that ships should be built of iron, but the proposal was received with derision. The _Vulcan_, built in 1818 at Faskine near Glasgow, is, so far as is known, the first iron vessel constructed for commercial purposes, and so well was she built that as recently as 1875 she was engaged in transporting coal on the Forth and Clyde Canal, and looked little the worse for wear. Her builder was one Thomas Wilson.

The first iron steamer, however, was the _Aaron Manby_, built in 1821 at the Horseley Iron Works near Birmingham, to the order of Captain Napier, afterwards Admiral Sir Charles Napier, and Mr. Manby. She was put together at Rotherhithe, and in May 1822 at Parliament Stairs took on board a distinguished party of naval officers and engineers, whom she conveyed for a trip of several hours up and down the river between Blackfriars and Battersea. A contemporary newspaper described her as “the most complete specimen of workmanship in the iron way that has ever been witnessed.” This little vessel was 106 feet long and 17 feet broad, and carried a 30-horse-power engine. Her wheels were of the type known as Oldham’s revolving bars. Her only sea voyage was to France under the command of Captain Napier. Upon arrival she was employed on the Seine or Loire. Another iron vessel intended for navigation on the Seine was shortly afterwards made in this country, and the parts sent to France to be put together.

Little appears to have been attempted in this country for some years in the way of iron shipbuilding, although in Ireland three or four small iron sailers or steamers were constructed for inland navigation purposes. But in 1828 John Laird of Birkenhead had his attention directed to iron shipbuilding, and completed his first iron vessel there the following year. Other builders followed where he showed the way, and in less than three years there were shipbuilders on the Thames, Clyde, and east coast of Scotland who were launching iron vessels, the great majority of which were sailing ships. The famous yards on the Cheshire side of the Mersey remained for some time the headquarters of the new industry. The first iron vessels for the United States--not the first iron-plated vessels, and this is a distinction which should be noted--were launched there, and so immediate was the recognition of the advantages of iron ships over wooden ones that by 1835 there had been built at Laird’s the first iron vessels for use on the rivers Euphrates, Indus, Nile, Vistula, and Don. They were small compared with the wooden vessels afloat.

The _Garry Owen_, built in 1834 by MacGregor, Laird and Co. of iron, was only 125 feet in length, 21 feet 6 inches beam, with two engines totalling 90 horse-power. There were no Lloyd’s rules as to scantlings for iron steamers in those days, and builders put in as much material as they thought necessary for the strength of the vessel, which usually meant a liberal allowance. The _Garry Owen_ was not much to look at, but she was very strongly built, a circumstance which had a great deal to do with the development of iron steam-ship building. She nearly came to grief on her first voyage, for she was overtaken by a violent storm, which drove her and several other vessels ashore. These others were of wood. Some of them were soon pounded to pieces by the heavy seas, and those that escaped total loss were badly damaged; but the _Garry Owen_, though bumped and dented somewhat, was able to get afloat again little the worse and return under her own steam.

If a steamer strongly built of iron could survive a storm and stranding which ended the careers of several wooden ships of larger dimensions, it was admitted that there was no valid reason why other iron vessels should not prove equally safe, especially if they were larger. It was considered that iron steamers might find useful employment in short voyages, and several were built.

One of the chief of these vessels was the _Rainbow_, launched in 1837 for the London and coastal trade. She was 185 feet long by 25 feet beam, and of 600 tons, with engines of 180 horse-power.

The use of iron in construction was not the only factor in the tremendous change which was coming in shipbuilding. A new form of propulsion was necessary, and it was found in the screw propeller.

Before considering this, however, the development in the construction of paddle-wheels and of the engines designed for paddle-boats may be noticed.

The ordinary paddle-wheel had the floats fixed upon the radial arms, but it was soon found that an improvement could be made by causing the floats to assume a position vertical, or nearly so, at the moment of contact with the surface of the water, and to retain that position until the float had left the water. To effect this the floats are not bolted to the arms but pivoted, and are retained in the required position by means of levers operated by an eccentric pin. By this means a much greater propulsive force was exerted. The old style of paddle-wheel with fixed floats is now very seldom employed. These wheels are now only to be found in vessels in which the expense of construction has to be cut down to a minimum, or in a certain type of steamer plying in shallow rivers, where the wheel is rather large, and the dip of the float slight; but here again economy of construction may count for more with the proprietor of the boat than the increased speed he could obtain with the more expensive feathering wheels. Many of the modern wheeled vessels have floats of steel, but in the great majority of cases wood is employed, elm being largely used for this purpose. The floats are usually about four times as long as they are broad. Various forms are used, some being left square at the corners, others are rounded, others again have the outer edge elliptical in shape, and the experiment has also been tried with a fair measure of success of inclining the floats to the axis of the wheel, instead of having them parallel to it. The advantages claimed for this last method are that the stream of water formed by the rotatory motion of the paddles is driven slightly away from the sides of the vessel, instead of in a direction parallel with her length. Wheels of this type, however, lose much of their effectiveness when the engines are reversed. Radial wheels are sometimes made with the floats adjusted so that they enter the water almost perpendicularly, but they are much more oblique under this arrangement when leaving the water.

A difficulty which paddle-vessels have to contend with is that of securing a proper immersion of the floats. For a vessel in smooth water the immersion of the top edge is usually calculated at about one-eighth of the breadth of the float; but for a vessel intended for general sea service, an immersion of not less than half the breadth of the float is allowed, that is to say, the float at its moment of deepest immersion has a height of water above it equal to half its diameter. If the float goes much deeper the efficiency of the wheel becomes impaired. This is a point which has to be taken into consideration in designing paddle-boats, so that the maximum power shall be available when the vessel is fully laden, and shall not be much lessened when the vessel is running light. The earliest steamers suffered greatly in this respect as their designers had not discovered the right size of wheels or floats to suit the hulls. A loaded vessel consequently went very slowly owing to the great depth to which her floats were immersed. To overcome this difficulty an ingenious system of what can best be called reefing was invented. Affixed to the axle of the wheel was a rod with an arrangement of cogs at the end, and these fitted into a series of teeth in rods affixed to the floats, so that it was a simple matter to expand or contract the effective diameter of the wheel by altering the position of the floats as required. The same result has sometimes been obtained by a system of levers, but the toothed wheel business was the older. It was tried on a few of the earlier boats on the Clyde, not always, however, with success.

A peculiarity of some of the larger paddle-wheels in use in America is that they are not only of much greater size than those in use in Great Britain in proportion to the size of the boat, but they have a proportionately less immersion and the wheel is constructed in a very different fashion. The floats, instead of being of one piece, as here, are constructed of three narrow fixed strips, two of which are on the same radius but have a space between them equal to the breadth of the third strip, which is placed a few inches behind the vacant space. It is contended that this method disturbs the water less than the broad float and increases the propelling efficiency. Probably the most notable instance is the great wheel of the _Sprague_.

Referring now to the construction of the engines of the earliest boats, Symington’s _Charlotte Dundas_ used a horizontal direct-acting engine, and the general arrangement of her machinery would be considered creditable even at the present day.[79] The engine of the _Savannah_ was of the inclined direct-acting type. The type of engine which Newcomen invented has been retained for many years, but the oscillating or walking beam which is such a conspicuous feature of nearly all the American river craft has been placed by engineers in this country below the crank axle instead of above. The type of engine with the beam below the crank axle is known as the side lever. It is a type peculiarly suitable to paddle-wheels, and this being the only method of propulsion adopted on this side of the Atlantic for many years, there was little change for a considerable period in the shape of the engines, which therefore attained to a high stage of perfection until the limit of their profitable employment was reached. When larger engines became necessary, in consequence of the rapidly increasing size of vessels, the great weight of the side-lever engines proved a serious drawback.

[79] Sennet and Oram’s “The Marine Steam-Engine,” 1898.

Engineers were not long in devising a more compact form of machinery, and direct-acting engines were introduced, these involving the abandonment of the use of the heavy side levers. As the side-lever engines were made larger it became customary to use two beams, one on each side, and a rod from one end of each of these connected with a cross-piece at the top of the piston-rod. The other ends of the double beam were united by a cross-piece which carried from its centre the rod or lever which worked the crank of the paddle-shaft. Where it became necessary to use two engines in one vessel, they were so arranged that while one rod and crank were at their period of least activity, the other pair were exerting their greatest effort. The system of condensation of steam, which it would take too much space to describe in detail, is also a matter of great importance in determining the power of the engine, but the principle upon which the condensation is effected is well known, and the various methods of condensation can easily be ascertained from the numerous handbooks on engineering.

Another early form of marine engine was that in which the side levers were arranged as levers of the third order, the fulcrum being at one end and the steam cylinder placed between it and the connecting-rod. The peculiar motion thereby given to the machinery caused this type to be known as the grasshopper engine, from a fancied resemblance to the long legs of a grasshopper. The direct-acting engines were much more compact, more powerful, and lighter than the old side levers. The necessity of providing a connecting-rod of sufficient length was met by Messrs. Maudslay by the provision of two cylinders. The cross-head was not unlike the letter =[T]=, the foot of which passed down between the cylinders, and the lower end of this was fitted with a journal from which the connecting-rod extended to the crank in the axle. A still further improvement was made when the oscillating engines were invented, which form an even more compact and simple type. Messrs. Maudslay fitted a pair of oscillating engines in 1828 into the paddle-steamer _Endeavour_, and subsequently into several ships. This form of engine was improved upon by Mr. John Penn, the famous engineer at Blackwall, and the perfection which he gave it has not been surpassed.

The great feature of this method is that the trunnions are hollow, and the steam is admitted to and exhausted from the cylinders through them. The connecting-rod is dispensed with and the upper end of the piston-rod acts directly on the crank pin. This type of engine is the most economical for space and weight that has yet been provided for paddle-wheel engines, the majority of which of late years have been made on this system.

Its adaptability for certain classes of work has given the paddle-wheel a long lease of life. Paddles are peculiarly suitable for certain conditions, such as smooth waters and shallow rivers, where speed and light draught combined with considerable carrying power are essential. The Indian rivers, for instance, early demanded suitable steamers, and the paddle-steamers _Lord W. Bentinck_, _Thames_, _Megna_, and _Jumna_ were built of iron in 1832 for the East India Company for the navigation of the Ganges. They were designed and constructed by Maudslay, Sons, and Field, and fitted with oscillating cylinder engines of 30 nominal horse-power. They were flat-bottomed and were shipped to India in pieces. They were 120 feet in length, 22 feet beam, and had a draught of 2 feet. Their tonnage was 275, builders’ measurement.

The steamers sent to India, however, from over sea were not the only ones in that country.

As far back as 1820 there was launched at Bombay the first steamer built in India; she was intended for service on the River Indus. Her engines were designed by a Parsee. She must have been a familiar object to many hundreds of Anglo-Indians during her long career. She was only broken up as recently as 1880, and her end came not through weakness but through her supersession by more modern and commodious boats.

There is a custom peculiar to Bombay, and stated to be of Parsee origin,[80] of driving a silver spike into the stern of a vessel at its launch. This is said to be analogous to the placing of coins under the foundation-stone. The ceremony was observed at the launching of a paddle-steamer at Bombay in 1875, when a nail some seven inches in length and three-quarters of an inch in diameter was used, but whether such a ceremony took place at the launch in 1820 is not recorded. If it is a Parsee ceremony, however, it is quite likely to have been observed, for the East clings faithfully to its traditions.

[80] _Notes and Queries._

A paddle-wheel steamer built in 1859 for service on the Indus had a draught of only 20 inches. The hull was a frameless cellular raft, but the walls of the deck cabin were worked into the depth of the vessel, which was thus made a girder 200 feet in length, and by this contrivance the engine and boilers, weighing 150 tons, were supported. A couple of plate girders having a run of 115 feet were included in her middle length. These were 15 feet deep and formed the sides of the cabins, and they also projected under the deck for a distance of 35 feet. The hull of the vessel was practically a long, flat, shallow box; the stern was rounded and the keel was turned up about 2 feet to allow of the water rising easily. The bow was rather fine and designed on the wave-line principle. The engines were of 688 horse-power and the boilers had a pressure of 25 lb. The paddle-wheels were 14¹⁄₄ feet in diameter. Her load displacement was 331 tons and her draught when laden was only 24 inches.

The _Ly-ee-moon_, launched in 1860 by the Thames Iron and Shipbuilding Company, resembled in some respects the steam-yacht of the Queen. She was built for Messrs. Dent and Co. for service between Hong-Kong and Shanghai, and was 270 feet in length and 27 feet 3 inches beam with a draught of 12 feet 6 inches. She was of 1003 tons register and 1394 tons displacement; her oscillating engines had cylinders of 70 inches diameter, with a stroke of 5¹⁄₂ feet. She was the first merchant vessel fitted with Lindsay’s apparatus for scaling the boilers with superheated steam. The paddles were 22 feet diameter. She had two masts, the foremast carrying lower yard, topsail yard and topgallant yard, and the trysails reached to the topmast head and gave her a good spread of canvas. She also carried several guns, and the sponsons were so fitted that the guns could be worked on them in case of need. Her speed was from 18 to 19 miles an hour. She afterwards passed into the possession of the Japanese; the story goes that when she was making her first run with Japanese only on board, the Japanese engineers, being unable to stop the engines, put the helm hard over and sat down to wait with true Oriental patience until the steam gave out and she stopped of her own accord. The _Ly-ee-moon_ afterwards passed into Australian ownership and she ran for a long time in the excursion and coastal trade, and was finally wrecked in March 1886, when seventy persons lost their lives.

The paddle-steamer _Leinster_ was one of four constructed of iron for the mail service between Holyhead and Kingstown in 1860 by Samuda Bros. She had nine water-tight bulkheads. A vessel intended for this service, on which exceedingly rough weather is at times encountered, through which the vessels are driven at full speed in order to ensure the punctual delivery of the mails, has to be built very strongly to stand the strain of the rough seas. For this purpose the paddle-boxes were formed of iron plates internally, continued from the sides and bulwarks of the vessel together with a strong girder extending from each bow. Two of the four, the _Ulster_ and _Munster_, were withdrawn from the service in 1896-7 and turned into barquentines, their places being taken by larger vessels of the same names. The present bearers of the names are twin-screws and have triple-expansion engines. The engines of the former boats had each two oscillating cylinders, 98 inches in diameter and having a stroke of 78 inches, situated immediately below the paddle-shaft. They had each eight multitubular boilers bearing steam at 20 lb. pressure, arranged in pairs, four before and four abaft the engines, and with their ends backed to the sides of the vessel so as to allow of the stoking of the furnaces from a middle gangway. The paddle-wheels, 32 feet diameter, had fourteen floats 12 feet in length by 5 feet in width. The indicated horse-power was 4751, and the average speed in all weathers was 15¹⁄₂ knots.

Messrs. Scott, Russell and Co. launched at Millwall in September 1854, for a Sydney company, the steamer _Pacific_, which was expected to prove one of the fastest vessels afloat. She was 270 feet in length over all, breadth 82 feet, depth 34 feet, and tonnage 1200. She had oscillating engines of 450 horse-power nominal and over 1000 effective, four independent boilers, and her feathering paddle-wheels were of exceptional strength. She was estimated to steam sixteen miles an hour.

There was launched in the beginning of 1861 by Messrs. Pearse and Co. of Stockton-on-Tees, for the conveyance of troops on the lower Indus, a vessel which fulfilled the rather unusual requirements of a Government Commission appointed to discover the best means of navigating the Indian rivers which, though broad, are often shallow in places, and abounding in sandbanks. This vessel was 377 feet over all, beam 46 feet, breadth over paddle-boxes 74 feet, depth 5 feet, with a displacement at 2 feet draught of 730 tons. Her tonnage was 3991 under the old system of measurement. Her engines, by Messrs. James Watt and Co., were of 220 nominal horse-power, with horizontal cylinders of 55 inches diameter and 6 feet stroke. The paddle-wheels were 26 feet in diameter. The hull was of steel strengthened longitudinally by four arched girders, two of which carried the paddle-wheels, and the other two extended nearly the full length of the ship. Other girders strengthened her athwartships. She had no rudders in the ordinary sense, but was steered at each end by blades, which were raised from or lowered into the water at the required angle. The vessel had two tiers of cabins, and could accommodate 800 troops and their officers.

The paddle-steamer _Athole_, built by Messrs. Barclay, Curle and Co., Ltd., in the year 1866, was the first steamer to be fitted with the saloon above the upper deck. The credit for this improvement rests entirely with the late Mr. John Ferguson, who was then manager of the shipbuilding yard. So impressed were Lloyd’s that they desired Mr. Ferguson to patent his improvement, but this he refused to do as he considered it ought to be given to the shipbuilding world free of royalty.

Messrs. A. and J. Inglis were the builders in 1882 of the steel paddle-steamer _Ho-nam_, which has the distinction of being one of the few, and probably the first, English-built vessels constructed on the American plan. She was rigged as a two-master carrying fore and aft sails only. Her paddles were placed very far aft, and she was fitted with a walking beam-engine. She was constructed for the Chinese coastal trade and was of 2364 tons gross register, and was so successful that others of the same type followed.

These necessarily brief notices of some of the more remarkable paddle-boats of modern times, together with references in other chapters to paddle-steamers of still more recent years, are sufficient to show that the earlier form of propulsion has never been entirely superseded by the screw.

Possibly the earliest definite attempt to apply the screw for propelling purposes was made by David Bushnell in his abortive submarine exploit, an account of which appears in Chapter XII. hereafter;[81] but the propeller seems to have been very primitive. The screw propeller was also proposed in 1752 by the mathematician Daniel Bernoulli. A patent was granted in 1794 to William Lyttleton for a screw propeller which was caused to revolve by an endless rope passing round a wheel at the end of the axle. It was a distinct attempt to solve the problem and nearly succeeded, but it failed because there was too much of it. Had he been contented to use one pair of blades he would have obtained better results than by using two pairs of wide blades and two odd blades, arranged with three blades on either side of the axle so that his propeller became really a long spiral wheel. He also failed from the lack of sufficient power to drive the wheel, as manual labour only was used. Still, a boat fitted with this screw was tried at the Greenwich Dock, London, and a speed of two miles an hour was stated to have been obtained.

[81] See p. 376.

In 1800 Mr. Shorter, master of the transport _Doncaster_, brought out two plans of propulsion. One was in the form of two duck-foot paddles with an alternate movement; the other was a two-bladed screw propeller. The latter was attached to an inclined shaft carried by a universal joint to the deck of the vessel. One of these methods was said to have moved the _Doncaster_ at a speed of about a mile and a half an hour, the contrivance being driven by eight men running round a capstan. It is difficult to believe from the picture which accompanies his plan, dated 1800, that a transport of the size depicted could have been moved at half that speed with the apparatus shown, although the fact that it was mechanically propelled is attested by credible witnesses.

The first really successful screw-propelled boats were those of Colonel John Stevens, which were in operation on the Hudson River from the years 1802 to 1806, and were the first to be used for the effective navigation of the waters of any country. References have already been made to Stevens’ experiment with paddle propulsion in 1796. When he, Chancellor Livingston, Nicholas J. Roosevelt, and Isambard Brunel were making experiments in steam propulsion on the Passaic River, New Jersey, they tried a horizontal centrifugal wheel in a boat of 30 tons, drawing water from the bottom of the boat and discharging it at the stern. This is in its general principles similar to the plan that Mr. Ruthven tried in England on the _Waterwitch_ more than half a century afterwards. They also, unsuccessfully, attempted to use elliptical paddle-wheels.

Probably the best description of Colonel Stevens’ propeller is that which he himself contributed to the _Medical and Philosophical Journal_ of New York in January 1812. He refers to the “mischievous effects necessarily resulting from the alternating stroke of the engine of the ordinary construction” which induced him to turn his attention to the rotary principle of steam-engine construction. “For simplicity, lightness, and compactness the engine far exceeded any I have yet seen. A cylinder of brass, about eight inches in diameter and four inches long, was placed horizontally on the bottom of the boat: and by the alternate pressure of the steam on two sliding wings, an axis passing through its centre was made to revolve. On one end of this axis, which passed through the stern of the boat, wings like those on the arms of a windmill were fixed, adjusted to the most advantageous angle for operating on the water. This constituted the whole of the machinery. Working with the elasticity of the steam merely, no condenser, no air-pump was necessary; and as there were no valves, no apparatus was required for opening and shutting them. This simple little steam-engine was, in the summer of 1802, placed on board a flat-bottomed boat I had built for the purpose. This boat was 25 feet long, and about 5 or 6 feet wide. She was occasionally kept going until the cold weather stopped us. When the engine was in the best order, her velocity was about four miles an hour. I found it, however, impracticable, on so contracted a scale, to preserve due tightness in the packing of the wings in the cylinder for any length of time. This defect determined me to revert again to the reciprocating engine.”

Stevens and his son were crossing the Hudson in this boat on one occasion when the boiler, which was constructed of small tubes, gave way, and the next boiler was constructed with the tubes placed vertically. The engine was kept going for a fortnight or three weeks in the latter part of the summer of 1804, the boat making excursions for two or three miles up and down the river, and for a short distance he could get a speed out of it of seven or eight miles an hour.

Stevens’ early experiments with the screw propeller taught him that a vessel driven by only one screw has a tendency to move in a circle. This tendency is displayed in single-screw vessels to the present day. As is well known, a vessel driven by a right-handed screw will deflect slightly to the left, and a vessel driven by a left-handed screw will have a tendency to turn to the right. The explanation given of this peculiarity in the Stevens’ boat by Dr. P. Jones, who was superintendent of the United States Patent Office up to the date of its reorganisation under the law of 1836, in the _Journal of the Franklin Institute_ for 1838, is that this tendency was due to the lessened resistance, as the vanes of the propeller rose towards the surface, in consequence of the greater ease with which the water was removed out of the way. Consequently Stevens overcame this difficulty by using two such wheels placed side by side and revolving in reverse directions.

The original screw-engine is still in existence in the Museum of the Stevens Institute at Hoboken, New Jersey. The original boat, of course, has long since disappeared. A replica of it was tried with the old engine on the Hudson in October 1844, and attained a speed of eight miles an hour.

One great difficulty which early steamers had to contend with was that of boiler pressure. It should be remembered that the five distinct means Stevens proposed in connection with his screw propeller were:

1. The short four-bladed screw propeller.

2. The use of steam of high pressure.

3. The multitubular boiler.

4. The quick-moving engine connected directly to the propeller shaft.

5. Twin screws.

Not one of these means was applied to steam-ships until about forty years later, but all have contributed since their adoption to the success of the ocean navigation of the present day.

Stevens’ plan for working twin screws by a single cylinder is the most simple that could be devised. When the screw propeller came into use this plan was revived both in America and in Europe, and was known in France as the “Etoile” engine.

The principal reason for Stevens’ failure with the screw propeller was that there were no tools or competent workmen in America to construct properly the steam-engines that he planned between 1800 and 1806, and success was therefore impossible. He therefore reverted to the paddle-wheel with its slow-moving engine and the boilers then in use, carrying steam at a pressure of two or three pounds above the atmosphere. Stevens was not disposed to abandon the screw entirely, for he presented a plan in 1816 to the United States Government for a warship propelled by that means, but nothing came of it.

In the spring of 1825 an advertisement appeared in the _Times_ offering a hundred guineas for a means of propelling vessels without paddles, and in that year a company was formed for applying the gas vacuum engine to canal navigation.

Some of the earlier steam-engine-propelled iron vessels were strange craft. Designers and builders felt that they were entering upon new ground, and being less trammelled by tradition allowed their fancy free play. Their plans were occasionally daring in their originality and came astonishingly near to achieving success.

A freakish-looking vessel was launched on July 15, 1844, from the yard of her owner and builder, Mr. Cootes, at Walker-on-Tyne. She was a collier, built of iron, and carried a screw propeller driven by a small engine. On this account she is said to have been the first iron screw collier, antedating by some years the _John Bowes_, to which the honour is usually given. This ship was confessedly an experiment and was named the _Q.E.D._, and as her name was not changed during her career she no doubt gave satisfaction. The sea-borne coal trade was largely confined to wooden brigs of comparatively small tonnage. The _Q.E.D._ was barque-rigged, “with taut masts and square yards, the masts raking aft in a manner that is seldom seen except in the waters of the United States. She was provided with a 20-horse-power engine by Hawthorn, which turned a propeller (screw), a compound of several inventions, having four flies or flaps at right angles with each other, the bend of each flap at an angle of 45 degrees from the centre.”

On her first voyage to London,[82] when she had about twenty keels of coal on board, she grounded on the Gunfleet Sands, but was refloated undamaged after some of her cargo had been thrown overboard.

[82] Mr. Charles Mitchell, afterwards head of the shipbuilding firm
which amalgamated with Sir W. G. Armstrong and Co. under the style of
Armstrong, Mitchell and Co., Ltd., went to sea in this vessel for one
or two voyages, to watch the behaviour of her engines.--“The Making
of the River Tyne,” by L. W. Johnson.

Constructionally she presented several very novel features, which embodied the iron shipbuilding science of the time. Her over-all length was 150 feet, beam 27 feet 6 inches, and with the 340 tons of coal on board she was constructed to carry, she drew 11 feet 9 inches aft and 10 feet 3 inches forward. She is said to have been the first water-ballast vessel, for her hold was divided into separate chambers and each chamber had a false floor, between which and the hull was the space for water-ballast. The water, which was her only ballast, was admitted through taps and was pumped out by her engine. This was just a small steam auxiliary, capable of giving her a speed of four knots in a calm. Her mizzen-mast was of iron and hollow and was used as a funnel for the engine fires, so that when her furnace was going her mizzen rigging appeared to be on fire. Her bows had a sharp wedge-shape with considerable sheer, her stern overhung to an unusual degree, and her counters were very flat so as to lift her stern to the sea. The stern bore an armorial bearing with the motto “Spes mea Christus,” and “_Q.E.D_ of Newcastle.” The cabin was commodious, with a raised roof surrounded with window lights, and had four sleeping compartments, with a stateroom for the captain. A swinging compass was suspended, having a magnet on each side, and one before it, to counteract the attraction of the iron. Her shrouds were of wire rope served over with a strong double screw to each, a method in use to the present time. The main-mast from step to cap was 65 feet, the main yard 52 feet, and the mast, from the keel to the royal truck, was 130 feet.

As she steered with ease, sailed well, and exceeded expectations with the screw propeller, confidence was expressed “that the time is not far distant when our ships of the line will be fitted with engines and screws in a somewhat similar manner.” Four years after her launch her engines were removed and she was rigged as a barquentine. She ultimately went to the bottom of the English Channel in 1856.

As a steam collier the _Q.E.D._ can scarcely have been a success or her engines would not have been taken out of her. Probably the first real steamer to which the title can be applied was the _John Bowes_, built at Messrs. Palmer’s yard, formerly in the possession of Mr. Cootes. Messrs. Palmer Brothers and Co. established the fifth yard on the Tyne for iron shipbuilding purposes and the _John Bowes_ was their first vessel. Two steam colliers of a sort had already been built on the Mersey, but they were little better than steam barges. This, the first seagoing steam collier with a screw propeller, was 167 feet over all, 25 feet 7 inches beam, 15 feet 6 inches depth, and of 270 tons register. The firm started in 1851, and about this period the working of the new Midland coalfields began seriously to affect the sale of north country coal, which had hitherto been conveyed to London in small collier brigs. It now became imperative in the interests of colliery owners to devise some means by which the staple produce of the district could be conveyed to the metropolis expeditiously and regularly. Sir (then Mr.) Charles Palmer, who was connected with several large collieries in Northumberland and Durham, therefore designed the _John Bowes_ with a carrying capacity of 650 tons, and capable of steaming nine miles an hour. She was launched on June 30, 1852. The experiment proved a complete success, and to it may be attributed the important development of iron shipbuilding on the north-east coast which afterwards took place. The _John Bowes_ was the forerunner of a long list of screw colliers, and was speedily followed by the _William Hutt_, the _Countess of Strathmore_, and numerous vessels of a similar type.

Captain Blackett, R.N., speaking at the launch of the _John Bowes_, expressed the opinion that paddle-wheel ships were doomed altogether. The chairman, Mr. Charles M. Palmer, referred to the superiority of the vessel over the sailing brigs, and added: “The application of iron to shipbuilding, especially to colliers, gives great advantages. There being much more space than is required for cargo, the surplus in the _John Bowes_ is available for water-ballast, by placing an inner bottom, with compartments, thus saving much detention and expense, the water being pumped out by the engine used for the screw propeller. When this description of collier is brought into general use, and the coal merchants can be supplied with regularity, and, moreover, cannot take advantage of the fleets, they will no doubt purchase from the coalowners at a price on board in the north, and thus obviate the ruinous speculations now existing, and present the most effectual mode of regulating the trade. I am aware that in substituting iron screw steamers for wooden sailing vessels we are running counter to the wishes of many shipowners, but I am satisfied we are taking the right course; we have the public with us: and I am confident of success.” His confidence is justified by the history of the Tyne.

(PASSING PALMER’S SHIPYARD, WHERE SHE WAS LAUNCHED, 1852.)]

Numerous attempts were made to solve the problem of the proper application of the screw propeller. Most of them were fantastic and a few were even absurd. The difficulties that inventors had to surmount were so great that it is no wonder many gave up the struggle in despair, notwithstanding the obvious advantages of this method. They had to decide where the propeller should be placed so as to give the best results, without interfering with the steering powers of the rudder. They had to ascertain the best material for the bearings of the propeller shaft in order to avoid the wearing away or the overheating of the shaft and bearings through the friction caused by its revolutions; for worn bearings meant leakage and excessive vibration, and the latter meant an ever-increasing strain on the structure of the ship, this being particularly the case with wooden vessels.

By degrees these obstacles were overcome, but the questions of the number, size, and shape of the blades, their pitch, or theoretical forward movement in making a complete turn, their degree of immersion and their most efficacious speed, are taxing the brains of the most skilled naval engineers and architects of the present day. Obviously, these questions are of the highest importance to all students of marine engineering no less than to steam-ship owners. As the power of the engines increased other considerations had to receive attention, including the best material for the construction of the propeller and the best methods of building or casting it to stand the enormous strains imposed upon it by the work it had to perform.

Almost simultaneously John Ericsson, the famous Swedish inventor, and Francis Pettit Smith, a Middlesex farmer, were engaged in experiments. Mr. (afterwards Sir) F. P. Smith made, in 1836, a clockwork model of a boat with a screw propeller, and it was so successful that he built a steam launch in order to try the experiment on a larger scale. This boat, the _F. P. Smith_, was about 29 feet long and 5 feet 9 inches beam, and was tried in the Paddington Canal in 1837; its power was derived from a steam-engine with a cylinder having a diameter of 6 inches and a stroke of 15 inches. The propeller was of wood with two full turns, and was placed some distance in front of the sternpost, where it was driven by a system of bevel wheels from the engine to the shaft. The propeller lost a blade on one of its trips, thereby adding to the speed of the vessel, and this led Mr. Smith to instal another screw with one turn only, or a half-turn on each blade. A metal propeller was afterwards substituted, and the boat went from London to Folkestone and other places on the coast at an average speed of five to five and a half knots.

It is stated Mr. Smith built a vessel of 60 tons[83] which, with a screw propeller, attained a speed of seven or eight miles an hour and went from Blackwall to Margate in eight and a half hours, and that she also towed the _British Queen_ steamer into the West India Dock. This probably refers to the _F. P. Smith_, the assertion that she was of 60 tons being erroneous. The results of the experiment were so satisfactory that a syndicate was formed which took the matter up and brought out the Ship Propeller Company, to whose capital Messrs. Rennie, the shipbuilders, subscribed £2000.

[83] _Historic Times_, March 1849.

This syndicate built the steam-ship _Archimedes_, the first seagoing vessel driven by a screw propeller. She was of 232 tons, and had engines of 80 horse-power. The cylinders were 37 inches in diameter and of 3 feet stroke, and the screw, being geared in the proportion of a fraction over five to one, made 140 revolutions per minute to about 27 revolutions of the engine shaft. The screw was formed of plates of iron fastened to arms of wrought iron, keyed upon a wrought-iron shaft. The boiler was suited to the shape of the vessel. The engines, chimney, boiler, coal-boxes, driving machinery, and propeller weighed altogether rather more than 64 tons. The propeller was fitted in such a way that it could be brought on deck for repair or when not required for use. The ship was 125 feet over all and 22¹⁄₂ feet beam. Various types of propeller blades were tried with her, and she was also sent on a voyage round the ports of Great Britain to demonstrate the effectiveness of this method of propulsion. On this trip she called at Bristol, where the _Great Britain_ was under construction, and was thus the cause of the screw propeller being adopted for that ship.

One of the tests to which the _Archimedes_ was subjected was a voyage between Dover and Calais in the company of two of the Post Office packets, which she beat handsomely. She went from London to Portsmouth in 1839, and continuing her voyage round the ports of the British Islands, to provide ocular proof to all interested, put in at Plymouth, where she was boarded by Admiral Sir Grayham Moore and the Commander-in-Chief, who were then convinced of the usefulness of the screw.

The next year the _Novelty_ was built for the owners of the _Archimedes_ by Mr. Wimshurst at Blackwall, to demonstrate still further the seagoing merits of a screw-propelled vessel. Her two-bladed screw was placed as near the sternpost as possible, and one of its features was that it had only a quarter of a turn to the blade. Her boilers worked at a steam pressure of sixty pounds above that of the atmosphere, the highest then attempted, and up to then regarded as impossible for a steamer. She took a general cargo to Constantinople, to which port she was the first screw cargo boat to go; but as on her return objections were raised that the pressure was too high, other engines were substituted working at only a quarter of the pressure. She was one of the few vessels in which the mast was used as a funnel, her mizzen-mast being made hollow and of iron for the purpose: she is also said to have been the first vessel to be fitted with an iron mast.

John Ericsson in 1836 patented a propeller consisting of two drums from which projected seven helical blades connected by an external hoop. The blades were inclined in opposite directions, thus forming a double screw propeller, the propellers being placed immediately behind the rudder, which had the usual “shark’s mouth” to allow of steering. The shafts were made so that one passed through the other, the outer one being tubular. The drums revolved in opposite directions, that nearer the sternpost moving at a slightly faster rate than the after drum. This method of arranging the propellers was adopted with a view to avoiding the loss caused by the motion imparted to the water by the single screw, but it was found that the trouble caused by the contrivance was not worth the results obtained. Another drawback was that the extra friction induced by one shaft operating within the other was so great that the contrivance was practically useless where a high speed was desired. The steamer _Francis B. Ogden_ was tried with this type of propeller in 1837, and towed the American sailing ship _Toronto_, of 630 tons burden, on the Thames at the rate of five miles an hour. The _Francis B. Ogden_ was about double the tonnage and power of Smith’s boat, being 45 feet long and having a high-pressure two-cylinder engine giving the propellers about 30 revolutions per minute. Ericsson’s next experiment was with the _Robert F. Stockton_, which was built by Laird at Birkenhead in 1838. She was 63 feet long and of 33 tons, and had engines of 30 horse-power. Prior to this his screw boat towed the Admiralty barge with my Lords of the Admiralty on board on the Thames, but the effort to convince them of the practicability of the method was doomed to failure, since they had previously decided that as the power was applied at the stern the vessel would not steer.

The _Robert F. Stockton_ crossed the Atlantic under canvas in 1839, and after one of the screws had been removed as useless, she was employed for a quarter of a century as a single-screw tugboat on the Delaware, under the name of the _New Jersey_. Commodore Robert F. Stockton in that year induced Ericsson to resign his office in London as superintending engineer of the Eastern Counties Railway and go to the United States. Several vessels were fitted with his propellers for river and inland waters navigation in America.

Mr. Ogden, who was American Consul at Liverpool from 1829 to 1840, and at Bristol from 1840 to 1857, “is credited with having first applied the important principles of the expansive power of steam and with the employment of right-angular cranks in marine engines. In 1813 he received a patent for low-pressure engines with two cylinders, working expansively, and the cranks being adjusted at right angles, and in 1817 the first engine ever constructed on this principle was built by him in Leeds, Yorkshire. He submitted his plan to James Watt, at Soho, who declared at once that it was a beautiful engine and that the combination was certainly original.”[84]

[84] Appleton’s “Cyclopædia of American Biography.”

The definite adoption of the screw propeller, both for the Royal Navy and the Mercantile Marine, may be said to have taken place in 1840-41. For some years no bearings of brass or other metal could be got to stand the strain of the stern shaft, “and at one moment it seemed as if the screw must be abandoned and the paddle-wheel reverted to. Mr. Penn solved the problem by using lignum-vitæ wood bearings, which, lubricated by water, were found to act without any appreciable wear, and in this simple way the screw has already been able to reach a point of development from which we can now calmly look back upon the financial risks and terrors which beset the early days of steam navigation.”[85]

[85] _The Times._

The difficulty of steering screw-propelled vessels was considerable, principally owing to the method of placing the screw in an aperture in the deadwood, while at the same time retaining the full underbody aft. The full power of the screw could not thus be exerted, and the attendant churning of the water interfered with the steering power of the rudder. A system of double rudders was brought out in an attempt to solve the difficulty, but the disadvantages it possessed were against its general adoption. These rudders were hung respectively one on each side of the forepart of a somewhat extended sternpost, against which they lay when amidships, moving out as required to steer the ship, or both could be moved outwards to help to stop her. The sternpost was really a vertical hollow box through which the screw framing passed, the screw working behind it and beyond the rudders. Later improvements in shipbuilding rendered this device unnecessary.

The difficulty was solved by the simple expedient of placing the sternpost farther aft so as to give room for a greater space in the deadwood in which the propeller was to act.

The superiority of the screw to paddles was now being gradually admitted, and the number of small vessels fitted with screws increased. But no one had as yet dared to launch a large screw steamer for ocean voyages.

The honour of being the first to do this was gained by the Great Western Steamship Company. The _Great Western_, which has been mentioned in Chapter V, had been so successful that her owners felt justified not only in ordering another vessel but in determining that their new steamer should be the largest afloat and illustrate the latest theories of construction. There were already rumours of competition in the North Atlantic trade, and the Great Western directors did not intend to be forestalled. They decided to build an iron ship and it was accordingly announced that the _Great Western_ was to be followed by the _Great Britain_, of iron. This project was roundly condemned by the public. The fact that iron steamers were already in existence on Irish waters did not count for much. These might be good enough for Irish lakes and rivers but would be unfit for the Atlantic Ocean. The _Garry Owen_ was already forgotten.

The Great Western Company, however, persisted. The _Great Britain_ was designed by the younger Brunel and launched in 1843. Her length of keel was 289 feet, and length from figure-head to taffrail 320 feet. Her beam was 51 feet. The total depth from the under side of the upper deck to the keel was 31 feet 4 inches. Her tonnage was 3500 tons and her displacement at 16 feet was 2000 tons. Her cargo capacity was 1200 tons measurement, and her coal bunkers held 1000 tons. Since no shipbuilder had the necessary data for the construction of such a vessel, and shipbuilders as a whole were by no means favourably disposed towards iron ships, possibly because they had not the plant necessary for their construction, and as there was also a very widespread belief that a vessel of the size and dimensions of the _Great Britain_ could not be built of iron, the directors were unable to find a contractor who would undertake her construction. They were therefore obliged to instal the plant for building the ship and the engines also. She was built under the supervision of Paterson of Bristol, who was responsible for the _Great Western_. It was at first intended that the _Great Britain_ should be a paddle-steamer and her lines followed in several respects those of the best paddle-steamers of the day; though the _Great Britain_ herself contained so many novel features and was of so experimental a character that it could hardly be said that she followed anything.

Little had been done to demonstrate the power of the screw propeller, which for some unfathomable reason was considered to be suitable only for small vessels. However, after the construction of the _Great Britain_ had been commenced, the steamer _Archimedes_, fitted with Smith’s screw propeller, arrived at Bristol during her tour of the ports and demonstrated once and for all that the screw propeller could be used in seagoing vessels, and that, provided engines of sufficient power were installed, the screw propeller was more suitable for large hulls built to make ocean voyages than the best paddle-wheels then designed. But many years were to elapse before the shipping industry generally accepted this view.

The advantages of the screw, as proved by the _Archimedes_, were not, however, lost upon the enterprising directors of the Great Western Steamship Company, and they did not hesitate to order the designs of the _Great Britain_ to be altered so that she could be fitted with a screw instead of paddles. She was not built on a slip whence she might have been launched into the river, but in an excavated dock, and when she was afloat in the dock it was found that she was too big to be got out of it. That is to say, that having been fitted with her engines while still in dock, their weight immersed her to such an extent that she could not float out. This was owing to the dock officials’ delay in finishing alterations to the dock entrance, and not to any mistake or negligence on the part of the steamer officials. She was water-borne on July 19, 1843, and was christened by Prince Albert. The floating was attended by vexatious mishaps. The _Great Britain_ was attached by a hawser to the tug _Avon_, which was outside the dock, but at the critical moment the hawser broke. The bottle of wine thrown at the ship by the Prince fell several feet short. He threw another bottle of champagne, which struck the bows, and the wine and broken glass fell upon the men below, who were pushing against her sides to keep her off the dock walls.

Her figure-head consisted of the royal arms, flanked with a beehive, two cog-wheels, a dove, square, and the caduceus of Mercury in bronze on a white ground, with a scroll above and below. Her anchor was on Porter’s newly invented patent, which had been satisfactorily tested in the Navy for three years.

Her designer and builder took no chances. She was put together as strongly as possible, and it was well that this was so, for in her eventful career she was altered so frequently and so much that had she not been excellently put together she would very soon have succumbed to ship surgery. Her keel was formed of iron plates varying from three-quarters of an inch thick in the middle to one inch at the ends.

The plates of the hull under water were from three-eighths to half an inch at the top, except the upper plate, which was five-eighths of an inch. She was clincker-built and double riveted throughout. Towards the bow and stern and in the upper strakes the thicknesses were reduced gradually to seven-sixteenths. The ribs were of angle iron six inches by three and a half, by half an inch thick at the bottom of the vessel and seven-sixteenths thick at the top. The boiler platform was of plate iron supported upon ten iron keelsons. The hull was divided into five compartments by water-tight iron bulkheads. The decks were of wood and consisted of the cargo deck, two cabin decks, and the upper deck.

The beams for the support of the decks were bars of angle iron about three inches across with an additional bar measuring five inches by half an inch riveted on the side. The beams were from 2 feet 4 inches to 3 feet apart. There were also between the angle-iron bars and deck planks a series of diagonal flat tension bars, forming a continuous horizontal truss from end to end in each principal deck; these bars were riveted to the angle irons at the crossings and at the ends in order to prevent horizontal straining. The engine-room was strengthened by adding nine additional double ribs and sixteen additional reverse ribs riveted to the original framing. Her three boilers were each 33 feet in length, 10 feet wide, and 24 feet high; she had 24 fires, 12 fore and 12 aft, with a total surface of fire-box of 288 superficial feet. Her chimney was 8 feet in diameter and about 45 feet high; her four cylinders were 7 feet 4 inches diameter with a piston-stroke of 6 feet. Her two condensers of wrought iron three-quarters of an inch thick were 12 feet in length. The main wrought-iron shaft measured 15 feet 9 inches.

The engines were after Sir Mark Brunel’s patent in the position of the cylinders, except that they were disposed at an angle of about 60 degrees. The pitch of the screw was 13 feet 2 inches and its diameter 15 feet. It was six-bladed, and the screw shaft was revolved by four endless chains.

The crew numbered one hundred and thirty all told and she could accommodate three hundred and sixty passengers. Her principal promenade saloon was 110 feet in length by 48 feet at the widest part and 7 feet high, and had two staircases at each end. Her first-class dining-room was 100 feet in length by 50 feet wide and 8 feet high, with staircases communicating with those of the promenade saloon. Seeing how far she excelled all other steam-ships, she well merited being called by the newspapers a “stupendous steam-ship” of “unparalleled vastness.”

Her rig was as unique as her hull. She had six masts, of which only the second carried square sails, all the others being fore and aft rigged, and her one funnel was placed between the second and third masts. Five of her masts were stepped on turntables on deck so that they could be lowered and offer less resistance when going against a head wind. The lines of the ship were very fine, especially about the entrance from the forefoot. There was little of the “cod’s head and mackerel tail” style of build about her. She was admitted to be rather full amidships, for the accommodation of the engine, but was thought to approach as near the figure of least resistance as possible. The hull had a slight sheer and the vessel realised the expectation that she would be what sailors call “a dry ship.”

After getting out of the dock at last she left for London, where she arrived in January 1845 after a stormy voyage which tested her thoroughly. She remained five months at Blackwall, being visited by the Queen and Prince Albert, and left in June of that year with about eighty passengers for Liverpool, calling at a number of ports _en route_. She left the Mersey for New York on July 26 with from forty-five to sixty passengers (accounts differ) and about 600 tons of cargo. The voyage lasted 14 days 21 hours, and her average speed was nine and a half knots, but the engines were only worked at about 600 horse-power. New York was disappointed with her, as her six low masts contrasted unfavourably with the tall graceful masts of the American ships. She made the return journey in a day less.

On a subsequent voyage she broke one of the blades of her propeller, but as she made between ten and eleven knots, using both propeller and sail, it was decided when she was docked for repairs that her new propeller should have four blades only. In September 1846 she ran on the rocks in Dundrum Bay on the coast of Ireland, and was not refloated until August 1847. Thanks to her strong construction she was able to withstand a winter’s storms and a stranding of eleven months.

After being brought to Liverpool, she lay for some time at the North Docks and, as the Great Western Steamship Company thought the repairs would be too costly, she was purchased by Messrs. Gibbs, Bright and Co., formerly agents for the company, and they decided to refit her. The rolling plates attached to the sides of the hull were removed. An oak keel was bolted through upon the iron plates which had done duty for a keel when she was first built, to prevent rolling. Her bottom for about 150 feet had to be entirely renewed. The bows and stern were strengthened by double angle-iron framing secured by three tiers of iron stringers 2 feet 3 inches wide and five-eighths of an inch thick. Ten new keelsons were placed in the ship running her entire length, half as deep again as those formerly used. The various alterations resulted in the cargo capacity being increased by about 1000 tons, partly through the space saved by new boilers and partly through the construction of a deck-house 300 feet long and 7 feet 6 inches high. New bulwarks were erected higher than the previous ones. The number of masts was now reduced to four.[86] Two of the lower masts were iron cylinders and the two centre masts were ship-rigged, carrying royals. The fore and jigger were fore and aft rigged, but whereas the topsail of the foremast was shaped like a lugsail that of the jigger was carried on a gaff, according to a contemporary picture. The old engines were of 1000 nominal horse-power, but it is a question if they ever worked over 600 horse-power; the new engines were nominally 500 horse-power. Her new pair of oscillating engines were by John Penn and Son, engineers, Greenwich, and had cylinders 82¹⁄₂ inches diameter and 6 feet stroke. By the use of cog-wheels the screw shaft made three revolutions to one of the engine.

[86] According to a description and picture in the _Illustrated
London News_ she had five masts, the first, fourth, and fifth
masts being fore and aft rigged, but the fifth mast is probably an
incorrect addition to the picture. If she had five masts the number
must soon have been reduced.

The screw was three-bladed, 15 feet 6 inches diameter, and 19 feet pitch. There were six boilers, and her bunkers held 700 tons, and other accommodation enabled her to stow 510 tons more. To lessen the vibration experienced from the screw and machinery, eight new wrought-iron beams were placed transversely through the vessel, locking her sides together. The bases on which the machinery rested were made stronger, and she was further strengthened by massive iron entablature beams to the engines, buttressed by a framing of teak wood, each piece being 20 inches wide and 3 feet deep, running on either side of the engines transversely and diagonally to the sides of the ship. This solid timber extended 17 feet 6 inches on each side of the engine. The whole of this framing was bolted together and to the sides of the ship by wrought-iron bolts. The new arrangement of the boilers gave her a lessened coal consumption.

Little more need be said about this steamer. She made one voyage afterwards to New York and back, and being then acquired by Messrs. Antony Gibbs and Sons was placed in the Australian trade at the time of the gold fever, and continued a regular voyage between England and Australia for many years. She was afterwards patched up afresh and had her engines removed, but was then such a failure that though she got as far as the Falkland Islands, leaking badly, she was abandoned to the underwriters, and is now ingloriously ending her days as a coal hulk.