The steam vessels first built for the Navy were hardly worth calling warships and were of little or no value for fighting purposes. The first steam-propelled vessel in the Navy was the Monkey, of 210 tons, built at Rotherhithe in 1820 and fitted with engines of 80 nominal horse-power by Boulton and Watt. She had two cylinders of about 35¹⁄₂ inches diameter and 3 feet 6 inches piston-stroke. The Active, of 80 nominal horse-power, was launched by the same firm two years later, and in 1823 Messrs. Maudslay began with the Lightning that connection with the Royal Navy which was maintained as long as the firm was in existence. Up to 1840 about seventy steam vessels were added to the Government fleet, the majority of which were given side-lever engines and flue boilers with a steam-pressure of about 4 lb. to the square inch above the air-pressure. All these vessels were chiefly used for towage and general purposes, including mail carriage when necessary, and not as warships. There was a gradual improvement in the size of the vessels, and in 1832 the Rhadamanthus was constructed by Maudslay, Sons, and Field with engines of 220 nominal horse-power and 400 indicated. Her machinery weighed 275 tons.

The steamer Salamander appeared in 1832, and thereafter several similarly propelled wooden-hulled steamers were added to the Navy. Between 1840 and 1850 tubular boilers were generally adopted, the boilers being lighter and more compact than those previously in use, enabling the working pressure of the steam to be increased to ten or fifteen pounds above that of the atmosphere. All these vessels had paddle-wheels. Warships similarly propelled were adopted by other nations also, but with the exception of skirmishes with the natives of uncivilised or semi-civilised countries, vessels of this type were not tested in serious warfare until the war in the Crimea. Even then many of the British and French warships were stately wooden three-deckers. Such vessels of the attacking fleets as were paddle-driven usually suffered badly about the wheels when they ventured within range of the Russian guns; while those, chiefly despatch vessels and gunboats, which had screws, were comparatively safe so far as their propellers were concerned, but were too weak to engage the Russian batteries. Floating armoured batteries were therefore decided upon, some of which had screw propellers, single or twin, but from the marine, apart from the military, point of view, they achieved no great success.

Long before this, however, the screw propeller had proved so reliable and the advantage of its position below the water-line was so obvious that the Admiralty could no longer maintain its prejudice, and the warsloop Rattler was built at Sheerness in 1843 and fitted with a screw propeller. Her displacement was 1078 tons. Her engines, of 437 indicated horse-power, had a spur gearing by which the revolutions of the screw were increased to four times those of the crank. The steamer Alecto had paddle-engines of the direct-acting type, and of about the same power as those of the Rattler. The two vessels were made fast stern to stern with only a short distance between them to test the powers of their respective methods of propulsion, and although each did her best the screw boat towed the other at a speed of nearly 2¹⁄₂ knots. Of course a test of this sort could not demonstrate the superiority of one method over the other; all that it proved was that the Alecto was less powerful than the Rattler. A similar contest took place in the English Channel in June 1849, between the screw corvette Niger and the paddle-sloop Basilisk. The tug-of-war lasted an hour, and the Niger towed the Basilisk stern foremost 1·46 knots. These two vessels were very evenly matched in every respect, and the test in this case left no room for doubt as to which was the better method.

The first screw-propelled vessel in the British Navy was the Dwarf, built as the Mermaid by Messrs. Ditchburn and Mare at Blackwall in 1842, and as she attained at her trial the guaranteed speed of twelve miles an hour, the Admiralty fulfilled its promise and took her over and then renamed her. She was engined by Messrs. J. and G. Rennie. Her cylinders were vertical, of 40 inches diameter with 32 inches stroke, and the propeller was on their conoidal principle in which three blades are used, the surface of which, according to the specification, is “obtained by the descent of a tracer down the surface of a cone or conoid,” this giving an increasing pitch. The vessel was 130 feet long and of 164 tons measurement. Three years later she was used for a series of experiments with a variety of screw propellers.

Of the many inventions brought under the notice of the Admiralty and of private shipowners, one which attained a considerable measure of success was the contrivance patented by Taylor and Davies in 1836, and known as a modified and improved form of Bishop’s disc engine. It was tried in a pinnace, the Geyser, built in 1842 by Rennie.

In this form of engine the steam chamber is partly spherical, and the end-covers are cone-shaped, while the chamber contains a piston or circular disc fitted with a central boss that fits into spherical seats made in the covers, and a projecting arm placed at right angles to the disc engages with a crank arm on the screw shaft. A fixed radial partition intersecting the disc divides the chamber into four cells, to which steam is admitted by a slide valve. In 1849 H.M.S. Minx was equipped with one of these engines having a disc of 27 inches diameter, in addition to the high-pressure engine, and coupled to the propeller shaft in such a manner that it was not necessary to disconnect the horizontal engines. With the disc engine the vessel attained a speed 11 per cent. higher than without. Improvements in other engines, however, rendered inevitable the relegation of the disc engine to the list of superseded contrivances.

In 1838 Mr. John Penn’s oscillating engines with tubular boilers were fitted in some of the boats running above London Bridge, and attracted the attention of the Admiralty. The Admiralty yacht Black Eagle was turned over to him and he installed, instead of her former engines, oscillating engines of double their power, with tubular flue boilers, the change entailing no addition to the weight or engine space. The advantages of this installation were so great that many other vessels were similarly treated, among them being the royal yacht Victoria and Albert. His trunk engine, designed for the propulsion of warships carrying a screw, and capable of being placed below the water-line so far as to be out of reach of hostile shot, achieved an even greater success, and in 1847 Mr. Penn was instructed to place engines of this type in H.M.S. Arrogant and H.M.S. Encounter. These were so satisfactory that orders for engines were received for vessels ranging from a small gunboat, to be fitted with engines of 20 horse-power, to vessels like the Sultan, with engines of 8629 horse-power, and Neptune (ex Independencia), with 8800 indicated horse-power. Up to the time of his death his firm fitted 735 vessels with engines having an aggregate actual power of more than 500,000 horses. Among them were the Orlando, Howe, Bellerophon, Inconstant, Northampton, Ajax, Agamemnon, Hercules, Sultan, Warrior, Black Prince, Achilles, Minotaur, and Northumberland.

The barque-rigged steam frigate Penelope attracted as much attention in the Admiralties of the world as did the advent of the first Dreadnought a few years ago. She was an ordinary 46-gun frigate, and might have attained neither more nor less publicity than fell to the lot of other ships of her class. Her conversion in 1843, however, into a steam frigate made her famous. She was described as “a war steamer of a magnitude unequalled in our own or any foreign service, with an armament that will enable her to bid defiance to any two line-of-battle ships, especially as her steam will give her the means of taking a commanding position.”[95] She was one of the old French Hebe class of frigates, of which there were between thirty and forty lying in the various British ports in good condition, but considered useless, as larger frigates had been introduced by other powers. She was cut in half amidships and lengthened by 63 feet, the new middle space being devoted to her engines and boilers and to bunkers capable of holding 600 tons of coal. In addition to her crew of 300 officers and men, she could accommodate 1000 soldiers, with provisions and water for a voyage to the Cape of Good Hope. Her armament as a steamer consisted of two 10-inch pivot guns, each weighing 4 tons 4 cwt.; eight 68-pounders capable of firing both shot and shell, and fourteen 32-pounders. Her two steam-engines were believed to be of greater power than any yet made, having a combined horse-power of 625 horses. The cylinders had a diameter of 92 inches with a piston stroke of nearly 7 feet. The engines were direct-acting, and similar to those of the Cyclops, Gorgon, and other steam frigates in the Navy. A recess between the two foremost boilers contained the step for the main-mast, which therefore stood almost in the centre of the engine- and boiler-room. The funnel was placed abaft the main-mast, but the paddles were before it.

In 1845, Admiral Fishbourne adopted Scott Russell’s wave-line principle and made certain recommendations as to the lines on which a ship of war should be built. These were: “the buttock-lines are continuous curves, to minimise pitching; with the same object a fine bow and full afterbody are provided. To promote steady steering there is a long run of perpendicular side, a long keel, a lean forefoot, and a fine heel, while to insure powerful action of the rudder the draught of water is greatest aft; the floor rises aft from the midship section.”

But although shipbuilding of the modern type was initiated nearly three-quarters of a century ago, and iron vessels as warships had proved their utility more than once in the “affairs” of other nations, the British Admiralty remained faithful to wooden three-deckers long after a radical change in their allegiance would have been justified. It took a long time to convert the Admiralty. As early as 1842 an iron frigate was built by Laird at Birkenhead, called the Guadeloupe, for the Mexican Government. It was 187 feet long by 30 feet beam and 16 feet depth. An iron vessel, the Nemesis, was used in the Crimean War and was struck fourteen times by the enemy’s shot, the holes in every instance being clean and free from splinters. The Admiralty was not convinced, however, and as late as 1861 ordered nearly a million pounds’ worth of wood for warship construction. Other iron vessels carrying heavy guns, the Nimrod, Nitocris, Assyrian, Phlegethon, Ariadne, and Medusa, were built for the East India Company at Laird’s. The Admiralty had their first iron vessel, the Dover, built there, followed by the Birkenhead troopship, both paddle-steamers. The brigantine-rigged steam frigate Birkenhead was 210 feet in length between her perpendiculars, 60 feet 6 inches breadth outside the paddle-wheels, and 37 feet 6 inches inside the paddle-wheels, and had a depth of 23 feet. Her engines of 556 horse-power were by George Forrester and Co. A peculiar feature she had in common with several of her contemporaries was that she was clincker-built below water and carvel-built above. The unhappy ending of this ship is one of the most tragic events in the annals of the British Navy. She sailed from Queenstown, January 1852, for the Cape, having on board a portion of the 12th Lancers and of nine infantry regiments. She struck a pointed rock off Simon’s Bay, South Africa, and of the 638 persons on board no fewer than 454 of the crew and soldiers perished. The remainder, many of whom were women and children, were saved by the boats.

The honour of being the first British steam iron warship belongs to the Trident, a paddle-steamer, launched from Ditchburn and Mare’s shipbuilding yard at Blackwall in December 1845. Her length was 280 feet, the length of engine-room 45 feet, her beam 31 feet 6 inches, her breadth over paddles 52 feet 6 inches, her depth of hold 18 feet, and she was of 900 tons burden, including machinery, coals, water, guns, and stores. Her displacement at launching was 385 tons; the engines of 330 horse-power had oscillating cylinders, and her boilers were of a tubular pattern. She was designed by the builders. Her ribs were double, each rib being composed of two angle irons 4 inches by 3¹⁄₂ inches by half an inch thick, riveted together, and in one entire length from the gunwale to the keel, there being 270 pairs of these double ribs. The iron skin was three-quarters of an inch thick at the keel, and half an inch at the gunwale. The skin contained 1400 plates of iron which were riveted to each other and to the ribs and the keel by 200,000 rivets. Each rivet was wrought red-hot and required the united labours of three workmen and two boys to fix it in its corresponding hole. The price of iron when the ship was commenced was £8 10s. per ton, and when it was launched £16. The Trident carried two long swivel guns of 10-inch bore, one forward and one aft, to fire in line with the keel, and had also four 32-pounder broadside guns.

The Greenock, built by Scott, Sinclair and Co. at Greenock in 1849, was a second-class steam frigate and was the first steam frigate ever launched on the Clyde for the British Navy. Her length was 213 feet and her tonnage 1413 tons Admiralty measurement, with engines of 565 horse-power by the same builders. The screw propeller was 14 feet in diameter, constructed on F. P. Smith’s principle, and though it weighed seven tons, could be disengaged from the machinery and raised from the sea with ease. “The funnel also is to have some peculiar mode by which its hideous and crater-like physiognomy can be made at once to disappear, and leave the ship devoid at once of this unsightly feature, and of those cumbrous excrescences, paddle-boxes, giving her all the appearance and symmetry of a perfect sailing ship.”[96] Her figure-head was a bust of the late Mr. John Scott, father of the head of the firm who built her. The keel, stem, and stern were of solid malleable iron, measuring 5 inches thick by 9 inches deep. The Greenock was the only one of four vessels ordered by the then Board of Admiralty, to be fitted as a frigate and propelled with full power. She was armed on the main deck, and her model was so designed as to enable her to fight her bow and stern guns in line with the keel, in which important qualification she stood almost alone in the Navy.

The value of private shipbuilding yards able to undertake Admiralty work at short notice was abundantly proved during the Crimean War.

“In 1854, at the commencement of the Crimean War,” said the Times in an article on the building of warships in private establishments, “when Admiral Napier found himself powerless in the Baltic for want of gunboats, it became imperative to have 120 of them, with 60 horse-power engines on board, ready for next spring, and at first the means for turning out so large an amount of work in so short a time puzzled the Admiralty. But Mr. Penn pointed out, and himself put into practice, an easy solution of the mechanical difficulty. By calling to his assistance the best workshops in the country, in duplicating parts, and by a full use of the admirable resources of his own establishments at Greenwich and Deptford, he was able to fit up with the requisite engine-power ninety-seven gunboats. This performance is a memorable illustration of what the private workshops of this free country can accomplish when war with its unexpected requirements comes upon us.... Altogether during the Crimean War 121 vessels were fitted with engines for our Government by Mr. Penn.”

Two paddle-wheel gunboats, Nix and Salamander, were launched in 1851 by Messrs. Robinson and Russell for the Prussian Government, which exchanged them during the Crimean War for a frigate called the Thetis, and they were renamed Recruit and Weser. They were double-ended and could steam in either direction without turning. The paddle-frigate Dantzig, built by the same firm for the same foreign Government, had the peculiarity of being able to carry guns on her sponsons. The last wooden battleship built for the Navy was the Victoria, 121 guns, launched in 1859, commissioned in 1864, and discarded in 1867. She was engined by Maudslay with horizontal return connecting-rod engines indicating 4400 horse-power and giving her a speed of 12 knots. The Bann and Brune were built by Scott Russell as improvements on the Salamander, and were on the longitudinal system with wave-lines, and they had internal bulkheads separating the engine and boiler rooms from the bunkers.

The success of the floating batteries at the Crimea was held by the French to justify the construction of a sea-going ironclad, and the Gloire resulted. Experiments in America had shown the possibility of the plan, but the French naval architect, Dupuy de Lôme, considered that it would be sufficient to plate existing vessels. The Gloire was a big wooden ship cut down and iron-plated.

This stirred the Admiralty to activity and the Warrior was ordered. The launch of this vessel on the Thames was regarded as an event of national importance, and in spite of the cold day at the end of December 1860 on which she took the water, the attendance was exceedingly large, even the tops of the tall chimneys of the neighbourhood having been let out for the day to enthusiastic sightseers. She was frozen down to the ways so firmly that it was with the utmost difficulty that she could be got into the water at all. Tugs, hydraulic presses, the hammering by hundreds of men on the ways, and the firing of cannon from her deck to start her by concussion were all tried separately and then together, and at last the ship glided slowly into the water. The beauty of her lines was remarkable as she floated in her light trim, and afterwards, when she was properly equipped and in sea-going trim, she was one of the most beautiful ships the country ever possessed. She was iron built throughout, frame and plating being alike of the metal. She was 420 feet over all, 58 feet in breadth, and 41 feet 6 inches in depth from spar deck to keel. She was of 6177 tons builders’ measurement. Her engines, which were of 1250 nominal horse-power, weighed about 950 tons, but her bunkers only held 950 tons, or enough coal for six days’ steaming. She was divided into twenty-seven water-tight compartments at the bows and stern, and as the whole of her sides were so armoured as to afford protection to the vital parts of the ship, it was stated that even if the fore and stern parts of the ship were shot away, the centre would remain as a floating battery.

The Waterwitch is chiefly remarkable for the trial given in her to Mr. Ruthven’s system of hydraulic propulsion. A small boat was fitted with the machinery and tried on the Thames. A vessel provided with the Ruthven apparatus was built to the order of the Prussian Government in 1853, and for many years worked satisfactorily on the Oder. The chief engineer of Portsmouth Dockyard, when testifying to the Government as to the capabilities of the Ruthven method, said it afforded extraordinary facilities for manœuvring under steam, and he saw no reason why a speed should not be attained with it equal to that of the paddle or screw. A vessel called the Seraing was built by the Belgian shipbuilding firm of Cockerill and fitted with a Ruthven propeller, and when tried against a paddle-wheel vessel of the same form, tonnage, and horse-power was found to have about 10 per cent. greater speed than the other. The testimony of the chief engineer of the Portsmouth Dockyard resulted in the Waterwitch experiment. The hull of this vessel was constructed by the Thames Iron Works and Shipbuilding Company, and the design of the engines and the construction of the enormous turbine wheel, of which the propeller consists, were entrusted by the Admiralty to Messrs. Dudgeon. The Waterwitch was built of iron and was of 778 tons measurement, 162 feet in length by 32 feet in breadth, and 13 feet 9 inches in depth. She was flat-bottomed, broad in proportion to her length, and double-ended and had a rudder at each end. Her armour consisted of a belt of plating 4¹⁄₂ inches in thickness at the water-line and centrally on her broadside, with armour-plated bulkheads across her upper deck, the object of the latter arrangement being to enable her to fight her guns over her deck in line with her keel, through gunports in the thwartship bulkheads as well as through broadside ports. For the machinery, and in the bottom of the vessel near the centre, was a long and shallow iron box with its length in the direction of the vessel. The lower side of this box had an immense number of small rectangular orifices, admitting water from outside and under the ship’s bottom, the passage of the water being controlled by valves which were only opened when the engines were at work. The turbine wheel drew the water in through the bottom of the vessel and ejected it through copper propulsion pipes and nozzles, through an aperture on each side of the ship, a little below the water-line.

The propelling power of the hydraulic wheel is obtained from the force and volume of the column of water ejected by the wheel from the discharge pipes, on a principle that a gun recoils on being discharged, but with this difference, that the recoil from the water-wheel is continuous. If the column of water were discharged towards the stern the vessel moved forward, and if towards the stem it moved in the other direction; if discharged in both directions the vessel remained stationary, and if discharged forward on one side and towards the stern on the other, the vessel turned either on her centre as on a pivot, or if the pressure were greater in one direction than in the other, in a circle the size of which depended on the pressure of the discharge from either set of nozzles. No reversing of the engines or of the hydraulic wheel was required under any circumstances, the direction and force of the discharge being regulated by a series of valves. The hydraulic wheel was fixed immediately over the sluice valves and water-box, and revolved in a cast-iron circular case 19 feet in diameter. The wheel was itself 14 feet 6 inches in diameter and weighed eight tons, and was fitted with eleven vertical or radial arms and blades. The engines were of 160 nominal horse-power, and steam was supplied by two ordinary tubular boilers. At her trial the Waterwitch covered the measured mile in Long Reach in 6 minutes 20 seconds. At other trials later in the day she averaged 9 knots.

The shape of the vessel and the fact that she could be steered in either direction with equal facility were of undoubted advantage from the point of view of manœuvring, but the trials can hardly be called successful so much as experimental, as it was ascertained that she would probably have done better had her nozzles been differently placed and provision made for altering the size of the nozzles according to the speed at which the vessel was required to travel. The machinery itself, however, worked beautifully.

The Government ordered a number of comparative tests to be made in which the efficacy of the Waterwitch method could be judged against that of the double-screw system installed in the gunboats Viper and Vixen, all three vessels being of the same size. The two gunboats were not the best of their kind as they had double sternposts with a cavernous recess between them and flat overhanging sterns.

Mr. M. W. Ruthven, son of the inventor of the system, it being under his father’s patent that the Waterwitch machine was built, in addressing the Institute of Marine Engineers a few years ago, said:

“My efforts to make a ship safe, from an engineer’s point of view, lie in the method of propulsion. My plans are to apply all the engine-power of the ship to pumps for propulsion, and which can be used for pumping out leakage and propelling at the same time. In the largest pump I have made, 800 indicated horse-power discharged 350 tons of water a minute, and propelled the vessel faster than her sister ships with twin screws. The hydraulic propeller is of greatest value for the highest speeds, and has the greatest power of control. As the hydraulic is capable of subdivision to a great degree, the greatest amount of safety is possible. After an experience of sixty years of hydraulic propulsion, I am still of opinion that it is the means by which greater safety can be obtained at sea, and by which the highest speeds can be obtained with safety and economy.”[97]

This, however, was said before such phenomenal speeds were obtained with turbines and combined turbine and reciprocating engines.

A number of lifeboats fitted with jet-propelling machinery have been built by, among others, Messrs. Thornycroft, and have given every satisfaction. Whatever be the advantages of the system, and they are many, the drawbacks are very great, and the hydraulic method has been generally condemned because of the friction engendered by the pumping of such large quantities of water, and the probability of the inlet orifices becoming choked by sand, mud, or floating matter.

Notwithstanding its evident advantages, the screw propeller, whether single or double, had many enemies. It was asserted to be the cause of premature decay in both wood and iron vessels, and stringent orders were even given to ship captains to use canvas except in extreme cases when steam was absolutely necessary. “Our screw navy is, therefore,” said a paper of that period, “more of a sailing than a steam navy.” The twin-screw arranged by Messrs. Dudgeon was claimed to have developed the principle in such a way as to leave no doubt of its superiority over the single propeller. Twin-screws were no new thing at this time. Captain Smith, known as “Target Smith” because of his movable target in use on the Excellent, had experimented with some with a considerable measure of success, but it was Messrs. Dudgeon who solved the problem of twin-screw propellers for ocean-going steamers. They demonstrated that as good results could be got from two small propellers as from one large one.

The first application of twin-screws on the modern principle was made by Messrs. J. and W. Dudgeon in the Flora in November 1862.

Twin-screws were tried by the Admiralty some years earlier in the construction of the iron-cased floating batteries, but were driven in those vessels by one motion from the engines. The adoption of the twin-screw in their case enabled the Admiralty to build vessels that required only a moderately light draught of water, and carried, for their tonnage, an enormous weight of armament and armour, besides the weight of their engines; but the vessels had no increased powers of turning nor could they manœuvre rapidly under steam in any circumscribed space. The double independent screws overcame these drawbacks.

A small vessel in the Clyde worked two screws also, with two rudders, the idea, as acknowledged by the adaptor, having been derived from the model exhibited in the Exhibition of 1851 by Mr. John Sturdee, master shipwright’s assistant at Portsmouth Dockyard.

An unusual degree of interest attached to the trial of the steam-ship Flora by reason of the fact that each of her twin-screws was to be operated by its own engine. In the light of future events it is worthy of note that up to this time it was thought that the twin-screw would be useful for smaller vessels and gunboats carrying six guns or less; whereas the Flora, as representative of ships capable of carrying large armaments of guns, with considerable engine-power, and a light draught of water, and with a power of manœuvring such as could not be possessed by a single-screw vessel, marked a step forward in the march of improvement which was destined to have far-reaching results, both in the Navy and the Mercantile Marine. So important was the trial deemed that the Admiralty sent special representatives to report thereon. The Flora was an iron vessel, 150 feet long, 22¹⁄₂ feet beam, and 13 feet depth, and of 365 tons. She had two independent engines and screws, the latter being placed one under each quarter, and therefore in front of the rudder, in contrast to the prevailing system of placing a single screw right astern and behind the rudder. The cylinders of the two engines were 26 inches in diameter, with a stroke of 21 inches; and the propellers were each of 7 feet diameter with a pitch of 14¹⁄₂ feet. She had two tubular boilers working at 30 lb. pressure, and one high-pressure boiler working at 50 lb. pressure, the latter boiler being intended to be used for producing a steam blast in the chimney and to dry the steam from the two common boilers. The engines were of 120 horse-power collectively. She was rigged as a fore-and-aft schooner. The principal test to which the vessel was subjected tried her capabilities of being manœuvred. With the helm hard over and the engines going full speed ahead, the first circle was made in 3 minutes 14 seconds, the next in one second less time, and the third circle in 3 minutes 16 seconds, the diameter of the circle being about three lengths of the ship, but slightly diminished each time. The ship was then tested with one screw working ahead and the other astern. One circle was made in 3 minutes 39 seconds, and another in 3 minutes 49 seconds; “in making these circles the action of the ship’s hull was extraordinary, the central part being stationary, and both ends moving round equally. The circle was made on a pivot from the ship’s midship section. The vessel was then put in a straight course, stopped, and from a state of rest the engines were started, one ahead and the other astern, the circle being completed in 3 minutes 55 seconds and the diameter being as before within the ship’s length.”[98] The Flora proved herself faster than any other steamer of her size and horse-power, and became, thanks to her speed, one of the most successful blockade-runners during the American Civil War.

The experiments in the Flora, and afterwards in the Hebe and Kate, which were of about the same dimensions and power, were considered so satisfactory that a trial on a larger and more important scale was made in the summer of 1863 with the Aurora. This was an iron vessel, 165 feet in length, with a beam of 23 feet, and a depth of 13 feet 6 inches. Her engines, of 120 collective nominal horse-power, drove two three-bladed screws, each independently of the other; the screws were 7 feet in diameter and had a pitch of 14 feet 6 inches. The cylinders were of 26 inches in diameter with a stroke of 21 inches. On her trials she steered equally well with either propellers or rudder, and in the matter of speed passed everything she came across, including the Sea Swallow, one of the fastest paddle-boats on the Thames. The distance from Tilbury to the Nore, twenty nautical miles, was done in 1 hour 17 minutes, “an almost unparalleled rate of speed, considering the vessel’s horse-power of engine and hull displacement.”[99]

The Experiment was the first twin-screw boat built for the Navy. The engines were direct-acting, horizontal, high-pressure, and drove two three-bladed propellers, having a diameter of 3 feet 6 inches. She was built by Dudgeon in February 1863.

Some interesting experiments were also carried out in February 1863 with a steamer called the Edith, built by Dudgeon with a view to testing further, for the benefit of the Admiralty, whose representatives were present, the advantages of the twin-screw for naval manœuvring purposes. This vessel was not constructed for the Navy, however, but for commercial service across the Atlantic. She was rather larger than the Experiment, being 175 feet in length, 25 feet in breadth, and drawing 9 feet aft and 6 feet 6 inches forward. The twin-screws, each driven by its own engine, were three-bladed and had a diameter of 8 feet 6 inches, and a pitch of 16 feet. On her trial run down the river with the Admiralty officials on board, a speed was attained of nearly 12 knots against the tide, and nearly 15 knots with the tide, the engines averaging 100 revolutions a minute under 28 lb. steam-pressure. The vessel turned a complete circle in 3 minutes 29 seconds with her own centre as a pivot, and then the action of both screws was suddenly reversed. Their action upon the vessel was instantaneous, the revolving motion of the ship being changed to the opposite direction with the greatest ease. The manœuvre was repeated several times, and the vessel thus represented a revolving battery mounted with heavy ordnance, too heavy for training upon any given object by ordinary appliances. The hull became the carriage for such heavy guns, and trained them upon any given point by revolving under the action of the screws alone.

The American Navy up to the time of the Civil War was not taken into very serious consideration by the other nations, but in that momentous struggle the Federals awoke to the need of thoroughly effective vessels and built them quickly. They were the last to take to iron ships of war but they more than made up for the delay. In scarcely a year after the launch of Ericsson’s Monitor, the first ship of its class possessed by the Federal Government, there were built, or building, close upon twenty of these vessels. Various modifications were introduced but the principle was the same. This was the turret on the deck, where the armament of the vessel was placed, it being sought to construct an effective battery for defensive operations rather than to build a sea-going ship.

The contest between the Confederate iron protected Merrimac and the Federal wooden warships, which ended disastrously for the latter, and the battle between the Monitor and the Merrimac proved that the old wooden three-deckers had become obsolete and that they would be perfectly useless against a steam ram like the Merrimac and harmless against an ironclad ram like the Monitor.

For a time rams and turrets were regarded as all-important. The extreme in this combination was reached in the French ironclad ram Taureau. She was one of the most peculiar warships ever constructed. Seen end on she looked like a tremendous buoy, surmounted by a turret, a funnel, and two masts. A side view showed that an immense bow extended forward as a long ram, and that the turret was situated near the bows. The prow was of bronze and weighed eleven tons, and projected some forty feet under the water. Her deck view represented her as almost pear-shaped, with cylindrical sides, and she had her greatest beam at about the water-line. She was iron-clad for about three feet above the water-line amidships and aft, but the turret and bows had 5 inch armour. Altogether she was about 197 feet long by 48 feet beam, and carried one heavy gun in the turret.

A combination of three-decker and ironclad ram was the French warship Magenta, constructed in 1862. She had an enormous ram like the Taureau and carried eighty guns, and was barquentine rigged.

In England, Captain Coles began in 1859 to urge the construction of vessels of the cupola or turret type, and after the lesson of the famous contests in America between the two ironclads, the British Admiralty decided to try Captain Coles’ boats experimentally. He advocated the cutting down of the three-deckers into one-deck ships, carrying on this one deck one or more turrets or cupolas in which the guns should be placed. These turrets were capable of being turned so that the guns in them could be fired in any direction, and he proposed that a portion of the bulwarks should be hinged in order that they could be let down when it was required to fire the guns, and thus form a sort of additional protection to that portion of the ship’s side above the water-line, while when raised they would add to the seaworthiness of the vessels by keeping the water off their decks. Vessels built according to Captain Coles’ plans, it was contended, would be floating defences “which would be at once thoroughly manageable, impervious to shot, movable with ease, and seaworthy. Nor would they be so monstrous and unsightly to a nautical eye as the inventions of our American cousins. They would be fitted with masts and yards, having the one peculiarity of being made of one uniform size, so that ships of all classes abroad could be furnished at depots, in case of accident, or ships meeting each other could exchange with or supply their comrades,” to quote from one of the descriptions published at the time. Another advantage was that the conversion of heavy frigates and line-of-battle ships into iron-plated vessels, fitted with the Coles shield, could be effected at a comparatively moderate cost. Experiments with the cupola were tried on the Trusty and Hazard with success. The standardisation of masts and rigging was another point on which Captain Coles laid stress. The cupola system had so much to recommend it that Sir William Armstrong wrote to the Times endorsing it as solving the problem of working the heaviest guns. Could shipbuilding have stood still at that period the system would have been an unqualified success, but the rivalry between armour-makers and gunmakers was so intense that no sooner did an armour-plate maker produce a plate impenetrable to existing guns and projectiles than the gunmakers set to work to produce a gun and projectile which should smash the armour plate.

The steam corvette Pallas, launched at Woolwich in 1865, differed materially from any other vessel hitherto constructed. She was originally intended to be built of iron, but as the necessary machinery was not then in existence at Woolwich, she was constructed of wood and iron-plated, and had a belt of armour to protect the most important parts. She was rigged as a ship so that she might keep at sea for a considerable time, the sails enabling her to economise her fuel. In order to increase her seaworthiness she was made high above the water, her fixed bulwarks being eighteen feet above the water-level. She was also designed to be able to fight end on. The engines were of 600 horse-power, and, to counteract the enormous strains the screw propeller was expected to impose, a new system of stern construction was adopted whereby the sternposts and deadwood were connected with the sides by internal iron bulkheads, decks, and flats, and external brass castings. The Pallas was 2372 tons burden, and was intended to be a faster vessel than any wooden frigate in the Navy. The fastest wooden frigate afloat and complete then was the Mersey, which once got up to 13¹⁄₄ knots an hour. The Pallas was provided with Mr. Reid’s new bow, known as the U bow from its shape. This bow gave considerable buoyancy where it was needed to support the ram, but its shape created a wave forward and thus militated against the vessel’s speed.

H.M.S. Minotaur, launched in 1865, was almost the last of the great sailing warships carrying a ram and having powerful auxiliary machinery. She had five square-rigged masts, and all five topsails were on the divided principle.

The German ironclad Prinz Hendrick, built by Laird Brothers of Birkenhead, and launched in October 1866, was barque-rigged, and was fitted with Captain Coles’ tripod masts. She was also fitted with revolving turrets, hinged bulwarks, and a sliding funnel.

The Hercules, begun in June 1866, and launched in February 1869, was one of the best specimens of the entirely iron-built, iron-armoured frigates the Navy possessed at that time. Her ram bow did not protrude so far as in former vessels and only weighed about five tons. The armour plating on the sides of the ship weighed 1145 tons. The total weight of metal worked into the ship was 4252 tons. The bulwarks were of wood, but below them the first two strakes were of plates 6 inches thick; next was a strake of 8-inch armour covering the lower portion of the main deck or central box battery; then two strakes of 6-inch armour, then a belt of 9-inch armour along the water-line, then a strake of 6-inch plates resting above the double skin of the hull itself. The 9-inch plates were backed by 10 inches of teak, inside of which was an iron skin 1¹⁄₂ in. thick, supported by vertical frames 10 inches deep and 2 feet apart, while further stiffening structures were also included. The engines worked up to over 7000 indicated horse-power. The vessel also afforded an illustration of the tendency to reduce the number of guns and increase their weight. To add to her steering capacities she had a balanced rudder which was itself jointed and hinged upon the line of pivot.

The carrying of such quantities of armour was against the maintenance of high speed at sea, and accordingly the unarmoured iron frigate Inconstant was launched later in the same year. She carried sixteen guns and was faster than any other warship afloat.

The Prussian ironclad Koenig Wilhelm, built by the Thames Iron Works and Shipbuilding Company, from designs by Mr. E. J. Reid, in 1869, was commenced for the Turkish Government, and was built on the longitudinal system, having a series of wrought-iron girders or frames extending from end to end of the ship. There was an inner skin on the inner sides of the frames and ribs, as though one ship was inside another. She was then the heaviest vessel ever docked in the Thames, as she weighed 8500 tons. Her armour was 8 inches thick amidships and tapered slightly towards the ends.

The year 1869 was remarkable for the introduction into the British Navy of large ironclads without masts or sails and relying upon steam alone for their propulsion, and these vessels also demonstrated the most perfect form then understood of the turret ship as applied to a sea-going warship of large capacity. The Devastation, built at Portsmouth, and the Thunderer at Pembroke, were the first of this class, and were claimed to be more formidable than any other warships in existence both for offence and defence. They were each of 285 feet in length and 4406 tons, as compared with the first ironclad Warrior, 380 feet and 6019 tons, and the Minotaur, of 400 feet length and 6021 tons. The Warrior’s armour was 4¹⁄₂ inches of hammered plate that would break under the impact of heavy shot; that of the Minotaur was 5¹⁄₂ inches of rolled armour, in each vessel there being a strong backing of teak and iron plating built into the frame. The two turret ships had 12 inches of rolled armour plating on a teak backing built into an immensely strong framing 18 inches thick, and the whole was backed up with an inner skin of iron plating 1¹⁄₂ inches thick. The thickest armour then in use in the French Navy was 8¹⁄₄ inches and was carried only by rams of the Bélier class. These vessels also included an improvement in the bracket-frame system of construction, first introduced in the Bellerophon by Mr. Reid. The “breastwork monitor” of the Devastation type was regarded as an improvement on the American types of monitors. The turrets were mounted on Captain Coles’ system and each turret carried two 30-ton guns. The ships were driven by independent twin-screws and had a speed of 12¹⁄₂ knots.

In 1870 the ill-fated Captain was lost. She was designed by Captain Coles and built by Messrs. Laird as a sea-going turret vessel. The principal armament was four 25-ton Armstrong guns carried in two turrets, one fore and one aft; these turrets were 27 feet diameter outside and 22¹⁄₂ feet inside, half the thickness of the wall consisting of iron plating. This ship behaved admirably on her trials and also on an experimental cruise, and was sent to sea with the fleet in September of that year. From some reason never explained satisfactorily she capsized without warning, and went down in a few seconds during a gale in the Bay of Biscay before daylight on the morning of September 7. Only nineteen of the 500 persons on board were saved, among the drowned being Captain Coles himself.

This disaster evoked such an amount of criticism as to the vessel’s stability and seaworthiness that no more of the type were constructed, the turret ships subsequently built being modifications of the principle.