CHAPTER IX

PROPELLING MACHINERY No aspect of old naval warfare is so difficult for the modern reader to visualize, perhaps, as that which displays the essential weakness of the sailing warship: its impotence in a calm. It was a creature requiring for its activities two elements, air and water. Ruffle the sea with a breeze, and the sailing ship had power of motion towards most of the points of the compass; withdraw the winds, and she lay glued to the smooth water or rolling dangerously in the heavy swell, without power either of turning or translation. For centuries this weakness told heavily against her and in favour of the oar-propelled vessel, particularly in certain latitudes. Through many years, indeed, the two types held ascendancy each in its own waters; in the smooth stretches of the Mediterranean the oar-driven galley, light, swift, and using its sharp ram or bow-cannon as chief means of offence or defence, was a deadly danger to the becalmed sailing ship; in the rougher north Atlantic the sailing ship, strong, heavy, capacious, and armed for attack and defence only along its sides, proved far too fast and powerful for the oar-driven rival. Progress--increase of size, improvement in artillery, the development of the science of navigation--favoured the sailing ship, so that there came at last the day when, even in the Mediterranean, she attained ascendancy over the galley. But always there was this inherent weakness: in a dead calm the sailing ship lay open to attack from a quarter where her defence lay bare. Ninety-nine times out of a hundred, perhaps, she could move sufficiently to beat off her attacker by bringing her broadsides to bear. The hundredth, she lay at the mercy of her adversary, who could, by choosing his range and quarter of attack, make her temporary inferiority the occasion of defeat. For this military reason many attempts were made to supplement sails with oars. But oars and sails were incompatible. They were often, seen together in early times, but with progress the use of one became more and more irreconcilable with the use of the other. The Tudor galleasse, though possessing in our northern waters many advantages over the galley type, had the defects inherent in the compromise, and gave place in a short time to the high-charged “great ship” propelled by sails alone. The sailing ship was by that time strong and powerful enough to risk the one-in-a-hundred chance of being attacked by oared galleys in a stark calm. It was only when the first steam vessels plied English waters that the old weakness became apparent again. It was then seriously urged that the ship-of-the-line should carry oars once more, against the attack of small steamers converging on her from a weakly defended quarter. [Illustration: SHIP AND GALLEY (From Tartagliá’s _Arte of Shooting_, English Ed., A.D. 1588.)] § The oar was in many ways an objectionable form of power. It was very vulnerable, its presence made manœuvring at close quarters risky and difficult; and apart from the necessity, on which the galley service was based, of a large supply of slave-labour for working them, oars and the rowers absorbed a large proportion of the available inboard space, to the detriment both of artillery and merchandise. Many attempts were therefore made, not only to substitute animals for men, for the work of propulsion, but to apply power in a manner more suitable than by the primitive method of levers: oars or sweeps. The paddlewheel was thought of at a very early date; a Roman army is said to have been transported into Sicily by boats propelled by wheels moved by oxen, and in many old military treatises the substitution of wheels for oars is mentioned.[131] In 1588 Ramelli, engineer-in-ordinary to the French king, published a book in which was sketched an amphibious vehicle propelled by hand-worked paddlewheels: “une sorte de canot automobile blindé et percé de meurtrières pour les arquesbusiers.” In 1619 Torelli, Governor of Malta, fitted a ship with paddles, and in it passed through the Straits of Messina against the tide. But Richelieu, to whom he offered his invention, was not impressed with its value.[132] Before this, Blasco de Garoy, a Spanish captain, had exhibited to the Emperor Charles V, in 1543, an engine by which ships of the largest size could be propelled in a calm: an arrangement of hand-operated paddlewheels. In Bourne’s _Inventions and Devices_, published in 1578, is the first mention of paddlewheels (so far as we know) in any English book. By the placing of certain wheels on the outside of the boat, he says, and “so turning the wheels by some provision,” the boat may be made to go. And then he proceeds to mention the inversion of the paddlewheel, or the paddlewheel which is driven, as distinguished from the paddlewheel which drives. “They make a watermill in a boat, for when that it rideth at an anker, the tide or stream will turn the wheels with great force, and these mills are used in France,” etc. It is possible, indeed, that this was the prior form, and that the earliest paddlewheel was a mill and not primarily a means of propelling the vessel. Early in the seventeenth century the mechanical sciences began to develop rapidly and as the century advanced the flood of patents for the propulsion of ships increased. “To make boats, ships, and barges to go against the wind and tide”; “the drawing and working of barges and other vessels without the use of horses”; “for making vessels to navigate in a straight line with all winds though contrary”; these are some of the patents granted, the details of which are not known. At last the ingenious Marquis of Worcester, who in 1663 was granted a patent for his steam engine, also obtained a patent for an invention for propelling a vessel against wind and stream. It has sometimes been inferred that this invention was connected in some way with the steam engine, and the claim has been made that the Marquis was one of the first authors of steam propulsion. This is not so. Contained in the description of the ship-propelling invention are two statements which dispose completely of the theory that steam was the motive force; first, that the “force of the wind or stream causeth its (the engine’s) motion”; secondly, that “the more rapid the stream, the faster it (the vessel) advances against it.” From this it appears that the Marquis intended to utilize the watermill as described by Bourne. From a study of the description of the apparatus it has been concluded that “a rope fastened at one end up the stream, and at the other to the axis of waterwheels lying across the boat, and dipping into the water so as to be turned by the wheels, would fulfil the conditions proposed of advancing the boat faster, the more rapid the stream; and when at anchor such wheels might have been applied to other purposes.”[133] If this reconstruction is correct, the scope of the propelling device was very limited. In Bushnell’s _Compleat Shipwright_, published in 1678, a proposal was made for working oars by pivoting them at the vessel’s side and connecting their inboard ends by longitudinal rods operated by cranks geared to a centre-line capstan. But the disadvantages of oars so used must have been apparent, and there is no evidence that this invention was ever put into practice. The obvious alternative was the paddlewheel, and though that device had been known and used in a primitive form long before the seventeenth century, it was continually being reinvented (especially in the ’nineties) and tried by inventors in various countries. Denis Papin turned his original mind to the solution of this problem. A paper on the subject written by him in Germany in 1690 is of interest. Discussing the use of oars from ships’ sides he notes that, “Common oars could not be conveniently used in this way, and it would be necessary to use for this purpose those of a rotary construction, such as I remember to have seen at London. They were affixed to a machine made by direction of Prince Rupert, and were set in motion by horses, so as to produce a much greater velocity than could be given by sixteen watermen to the Royal Barge.” Papin, who had suggested the atmospheric steam engine, also suggested the possible application of steam to propulsion. But it was left to others to achieve what he had to propose. His talent, it has been said, lay rather in speculations on ingenious combinations, than in the mechanical power of carrying them into execution on a great scale. In 1708 he laid before the Royal Society, accompanied by a letter of recommendation from Leibnitz, a definite proposal for a boat “to be moved with oars by heat ... by an engine after the manner that has been practised at Cassel.” What form this engine was to take, and how the power was to be transmitted to the oars, is still a matter of conjecture. Only this is known, that the proposal was considered in detail by the president, Sir Isaac Newton, and that on his advice no further action was taken.[134] In France it has been widely claimed that Papin actually engined a boat and propelled it over the waters of the Weser by the force of steam. His biographer states that on the 24th September, 1707, Papin “embarquait sur le premier bateau à vapeur toute sa fortune.”[135] But the statement is not correct. The misconception, like that which assigned to the Marquis of Worcester the invention of a steam-propelled vessel, was doubtless due to the fact that the inventor was known to be engaged in the study of the steam engine and of ship-propelling mechanism. The two things, though distinct in themselves, were readily combined in the minds of his admirers. It is generally agreed to-day, we think, even by his own countrymen, that Papin, though he may claim the honour of having first suggested the application of steam to ship propulsion, never himself achieved a practical success. In the meantime Savery in England had produced his successful engine. In his case, too, the claim has been made that he first proposed steam propulsion for ships. But in his _Miner’s Friend_ this able mechanician showed that he recognized the limited application of his steam engine. “I believe,” he says, “it may be made very _useful_ to ships, but I dare not meddle with that matter; and leave it to the judgment of those who are the best judges of maritime affairs.” But in propulsion by hand-operated paddlewheels Savery was an enthusiastic believer. In 1698 he had published, in a book bearing the title, “_Navigation Improv’d: Or the Art of Rowing Ships of all Rates, in Calms, with a more easy, swift, and steady Motion than Oars can_,” a description of a mechanism consisting of paddlewheels formed of oars fitted radially to drumheads which were mounted on the two ends of an iron bar placed horizontally across the ship. This bar was geared by mortice wheels with another bar mounted vertically as the axis of a capstan; rotation of the capstan was thus transmitted to the paddlewheels. Savery fitted this mechanism to a wherry and carried out successful trials on the Thames before thousands of people. But the Navy Board would not consider it. They had incurred a loss, it appeared, on a horse tow-vessel which had been in use at Chatham a few years previously: a vessel which towed the greatest ships with the help of four, six, or eight horses, and which, incidentally, may have influenced Savery in adopting the term “horse power” as the unit of work for his steam engine. The sanguine inventor made great efforts to interest the authorities, but without avail; the Surveyor rejected the proposal. So in an angry mood Savery published his book, with a description of his mechanism and an account of his efforts to interest the authorities, to show how one man’s humour had obstructed his engine. “You see, Reader, what to trust to,” he concluded, “though you have found out an improvement as great to shipping as turning to windward, or the compass; unless you can sit round the green table in Crutched Friars, your invention is damned of course.” The first detailed scheme for applying steam-power to ship propulsion was contained in the patent of Jonathan Hulls, in 1736. Though great credit is generally given to this inventor (who has even been dubbed the father of steam navigation), it does not appear that in reality he contributed much to the advancement of the problem; which was, indeed, still waiting on the development of the steam engine. Hulls’ notion, explained in a pamphlet which he published in 1737, was to connect the piston of a Newcomen engine by a rope gearing with some wheels mounted in the waist of the vessel, which wheels oscillated as the piston moved up and down. These wheels were in turn connected by rope gearing with a large fan-wheel mounted in a frame rigged out over the vessel’s stern, the fans in their lowest position dipping into the water. The oscillating motion of the inboard wheels was converted into a continuous ahead motion of the fan-wheel by means of a ratchet. With this machinery he designed to tow ships in harbours and rivers. It must, however, be remarked that the invention was never more than a paper project; and that if Hulls had tried to translate his ideas into three dimensions he would have encountered, in all probability, insuperable practical difficulties. One very original suggestion of his certainly deserves notice; as a special case he proposed that when the tow-boat was used in shallow rivers two cranks, fitted to the axis of his driving wheels, should operate two long poles of sufficient length to reach the bottom of the river; these trailing poles, moving alternately forward, would propel the vessel. Here is an early application of the crank. But in this case it will be noted that the crank is driven, and that it converts a rotary into a reciprocating motion; in short, it is an inversion of the driving crank which, as applied to the steam engine, was not invented till some years later. As before remarked, the whole problem of steam propulsion waited upon the development of the steam engine. In the meantime the application of convenient forms of man power received considerable study, especially in France. In Bouguer’s _Traité du Navire_ the problem was investigated of propulsion by blades or panels, hinged, and folding when not in use against the vessel’s sides; and in 1753 the prize offered by the Academy of Sciences for an essay on the subject was won by Daniel Bernouilli, for a plan on those lines. Euler proposed paddlewheels on a transverse shaft geared like Savery’s, by mortice wheels to a multiple capstan. Variations of this method were proposed by other writers and inventors, and some of the best intellects in France attacked the problem. But nothing definite resulted. The most valuable result of the discussion was the conclusion drawn by M. Gautier, a professor of mathematics at Nancy, that the strength of the crew was not sufficient to give any great velocity to a ship. He proposed, therefore, as the only means of attaining that object, the employment of a steam engine, and pointed out several ways in which it might be applied to produce a rotary motion.[136] In the course of time the problem marched forward to a solution. The first great improvement in the steam engine which rendered it adaptable to marine use was the invention by Watt of the “double impulse”; the second, Pickard’s invention of the crank and connecting-rod. By virtue of these two developments the steam engine was made capable of imparting to a shaft a continuous rotary motion without the medium of noisy, brittle or inefficient gearing. As soon as engines having this power were placed on the public market attempts were made to mount them in boats and larger vessels; steam navigation was discerned as a possibility. § Of the many efforts which were made at the end of the eighteenth century to apply steam power to the propulsion of ships a striking feature is their complete independence from each other and from the results of prior experience and research. Little information is available as to the results of various experiments which were known to be carried on in France at this time, and, with all respect, it is improbable that they contributed in any way to the subsequent evolution of the steam vessel. The Abbé Darnal in 1781, M. de Jouffroi in 1782, and M. Desblancs in 1802 and 1803, proposed or constructed steamboats. M. de Jouffroi is said to have made several successful attempts on the Saone at Lyons; but the intervention of the Revolution put an end to his undertakings. In Britain a successful attempt to apply the steam engine to the paddlewheel was made in 1788. In that year three men, combining initiative, financial resource, and a large measure of engineering ingenuity, proved the possibility of steam propulsion in an experiment singularly complete and of singularly little effect on subsequent progress. In the summer of ’87 a wealthy and inventive banker, Mr. Patrick Miller of Dalswinton, Edinburgh, had been making experiments in the Firth of Forth with a double vessel of his own invention, sixty feet long, which, when wind failed for sailing, was set in motion by two paddlewheels. These paddlewheels were fitted between the two hulls of the vessel and were worked by men, by means of a geared capstan. Miller believed that a boat furnished with paddlewheels and worked manually would be of great advantage for working in shallow rivers and canals. But the result of a sailing race between his boat and a custom-house wherry of Leith, in which his own sails were supplemented by the labours of four men at the wheels, convinced him that manpower was insufficient. His sons’ tutor, a Mr. Taylor, suggested the application of a steam engine. And being acquainted with an engineer named Symington, Taylor prevailed on his patron to engage him to mount a one-horse-power engine in a double pleasure boat, upon the lake at Dalswinton. The experiment was a complete success. “The vessel moved delightfully, and notwithstanding the smallness of the cylinder (4 inches diameter), at the rate of 5 miles an hour. After amusing ourselves a few days the engine was removed and carried into the house, where it remained as a piece of ornamental furniture for a number of years.”[137] Determined to pursue the experiment, Miller ordered a replica of the original engine on a larger scale, and this engine, with a cylinder of 18 inches diameter, was erected at Carron and fitted to a larger boat. This also was successful. But no further trials were made after ’89; for Patrick Miller, who had spent a large sum in order to establish the feasibility of the invention, decided to close his investigations, and to turn to other pursuits. No further attempt was made in Great Britain until 1801, when Lord Dundas engaged Symington to make a series of experiments on the substitution of steam power for horse towage of barges on the Forth and Clyde canal: experiments which resulted in the _Charlotte Dundas_. In this celebrated vessel a double-acting Watt engine, with its 22-inch diameter cylinder mounted horizontally on the deck, actuated, through a simple connecting-rod and a crank with a 4-foot throw, a paddlewheel which was carried in a centre-line recess at the stern. In March, ’03, Symington in the _Charlotte Dundas_ towed two 70-ton vessels nineteen miles against a strong head wind in six hours. Success seemed assured to him. His reputation was already high, and now an invitation came from the Duke of Bridgewater for eight similar tow-boats to ply on his canal. But the inventor’s hopes were disappointed. The Duke died suddenly, and the governing body of the Forth and Clyde canal vetoed the further use of steam vessels for fear of the damage the waves might cause the banks. Other bodies took the same view, and thus came to an end an important passage in the history of steam navigation. It is remarkable, considering the efforts which had been made by inventors from the sixteenth century onwards to improve on oar-propulsion for military purposes, that Miller, Symington, and their friends do not seem to have envisaged any use for steamboats other than as tugs on canals. It is remarkable that in the presence of this initial success neither the government nor the public showed any realization of the possibilities which it unfolded; that no attempt was made by commercial enterprise--even if, in the realm of naval strategy, such an innovation was regarded as impolitic or impracticable[138]--to develop its advantages and to secure an undisputed lead in the new application of steam power. [Illustration: THE “CHARLOTTE DUNDAS” (From Fincham.)] It was in America that the most persistent and continuous development took place, quite independently of efforts elsewhere and almost contemporaneously with those above described. America, whose geographical conditions made water transport relatively far more important than it was in Great Britain, lent a ready ear to the schemes of inventors. In 1784 James Rumsey, and shortly afterwards John Fitch, had already laid plans before General Washington for the propulsion of boats by steam. John Fitch, whose original idea was a steamboat propelled by means of an endless chain of flat boards, afterwards experimented with an arrangement, “borrowed no doubt from the action of Indians in a canoe,” of paddles held vertically in frames mounted along the sides of the boat and operated by cranks. In 1786 a boat thus equipped made a successful trial on the Delaware, and in the following year a larger boat, fitted with a horizontal double-acting engine with a 12-inch cylinder and a 3-foot stroke, giving motion to six paddles on each side, was publicly tried on the same river. The speed attained was very small. At last in 1790, still protected by a patent which granted him a temporary monopoly in steamboat building, Fitch succeeded in building a boat which was an undisputed mechanical success. Discarding the paddle-frame and adopting a beam engine to drive paddle-boards at the stern, he produced a steamboat which, after being tested and credited with eight knots’ speed on a measured mile in front of Water Street, Philadelphia, in the presence of the governor and council of Pennsylvania, ran two or three thousand miles as a passenger boat on the Delaware before being dismantled. It was a considerable achievement. But the excessive weight and space absorbed by the machinery prevented the boat from being a financial success; and, after a journey to France, then distracted by the Revolution, Fitch returned home to America and ended his days a disappointed and a broken man. Nevertheless, the work he did was of service to others. He proved that the ponderous nature of the machinery was the greatest obstacle to the propulsion of small craft by steam, and from his failure deduced the conclusion, on which later inventors were able to build, that the solution of the problem lay in the _scale_: that, “it would be much easier to carry a first-rate man-of-war by steam at an equal rate than a small boat.”[139] James Rumsey, a Virginian, carried out in 1775 the first practical trials of water-jet propulsion, a small boat of his plying the Potomac at a small speed by means of a steam pump which sucked in water at the bow and threw it out at the stern. But as he felt himself obstructed in further experiments by the patent rights which had been given his rival Fitch he came to England; where, financed by a wealthy compatriot and aided by James Watt himself, he produced in ’93 a boat which on the Thames attained a speed of over four knots. Unfortunately Rumsey died in the middle of his experiments. An individual of extraordinary qualities had now turned his attention to the problem of steam propulsion. In that same year a young American artist, Robert Fulton, who had come to England to work under the guidance of his countryman Benjamin West, wrote to Lord Stanhope informing him of a plan which he had formed for moving ships by steam. Lord Stanhope, well known as a scientific inventor, had recently been experimenting with a vessel fitted with a 12-horse-power engine of Boulton and Watt’s working a propeller which operated like the foot of an aquatic bird. A correspondence ensued. Fulton, whose self-confidence equalled his originality, illustrated by drawings and diagrams his ideas on the subject. At first, he said, he thought of applying the force of an engine to an oar or paddle which, hinged on the counter at the stern, by a reciprocating motion would urge the vessel ahead. But on experimenting with a clockwork model he found that, though the boat sprang forward, the return stroke of the paddle interfered with the continuity of the motion. “I then endeavoured,” he wrote, “to give it a circular motion, which I effected by applying two paddles on an axis. Then the boat moved by jerks; there was too great a space between the strokes. I then applied three paddles, forming an equilateral triangle to which I gave a circular motion.” These paddles he proposed to place in cast-iron wheels one on each side of the boat and mounted on the same shaft at some height over the waterline, so that each wheel would “answer as a fly and brace to the perpendicular oars.” And he stated that he found, from his experiments with models, that three or six oars gave better results than any other number. From which it is clear that the paddlewheel was evolved by Fulton from the simple paddle independently of suggestion received from previous inventors. Some time was to elapse before the results of his experiments were utilized. Attracted by the boom in canal construction then in vogue Fulton devoted his mind to that subject; though in this connection the idea of steam-propelled boats still occupied him, as is shown by a letter he wrote in ’94 to Messrs. Boulton and Watt, asking for an estimate of costs and dimensions of “an engine with a rotative movement of the purchase of 3 or 4 horses which is designed to be placed in a boat.” From England he went to Paris, to try his fortune at half a dozen projects. In ’98 he was experimenting on the Seine with a screw propeller--“a fly of four parts similar to that of a smoke-jack,” which gave promising results. This screw propeller, however, was as yet unrecognized as the propulsive medium of the future. It had already been patented in England by Bramah in 1785--“a wheel with inclined fans, or wings, similar to the fly of a smoke-jack or the vertical sails of a windmill”; and, hand-operated, it had actually been used in America in 1776 by Bushnell in connection with his submarine. But in 1802 Fulton had decided against the screw, and in favour of the paddlewheel. It was in this year that an introduction to an influential compatriot, himself an experimenter in steam propulsion, gave Fulton the opportunity to display his talents to their mutual advantage. Chancellor Livingston, U.S. Minister to France, was aware of the enormous advantages which would accrue to America (and to the happy inventor) if steam propulsion could be achieved economically. With Fulton’s aid he decided on building an experimental steam vessel in France, with a view to transferring to America for commercial enterprise the perfected results of their labour. A partnership was formed, the work proceeded; but the experimental steamboat, whose scantlings were unequal to supporting the weight of the 8-horsepower machinery placed on board, sank at her moorings in a storm. A second boat, stronger and bigger, attained complete success. Fulton promptly wrote to Messrs. Boulton and Watt asking them to export to America a 24-horse-power engine complete with all accessories, in accordance with his sketches; and with a brass air-pump suitable for working in salt water. Then, going himself to England, he visited Messrs. Boulton and Watt and gleaned what information he could as to the properties of their machinery; studied the newly published results of Colonel Beaufoy’s experiments on ship form and fluid resistance; and journeyed to Scotland to visit Symington and see the famous _Charlotte Dundas_. Armed with this knowledge, with all the experience of Rumsey and Fitch, and with the data from his own trials, Fulton brought to a successful solution the problem of steam propulsion on a commercial scale. It has been remarked that there was no element in the _Clermont_ or her successors so original in conception that it would entitle Fulton to be regarded as the inventor of steam navigation. Nor did he himself claim to be such. He was successful in fitting together the elements, the inventions of others. Science is measurement, and Fulton applied his data and measured with great insight, adapting his elements in the right manner and proportion to form an efficient whole. “He was the first to treat the elementary factors in steamship design--dimensions, form, horse-power, speed, etc.--in a scientific spirit; to him belongs the credit of having coupled the boat and engine as a working unit.” From Fitch he had learned the economy of size, and the advantages of enlarging the scale of operations; from Beaufoy, the importance of a fair underwater form, with a sharp bow and stern. From Symington, who generously took him for a trip in the _Charlotte Dundas_, he could not fail to have gleaned much practical advice and information; it is remarkable, in this connection, that, after a sight of Symington’s horizontal cylinder with its simple connecting-rod drive to the stern wheel, he should have adhered to the vertical cylinder and the bell-crank or beam for the transmission of the force: an initial divergence which was perpetuated, and which became the hall-mark distinguishing American from English practice for some years to come. Most of his knowledge he gained by his activities in England, and many writers have contested a claim--which so far as is known was never made by him--to the invention of the steamship. His achievements were well defined and legitimately executed, and the remarkable insight and initiative which he displayed in adapting the labours of others to serve his own utilitarian ends cannot, surely, deserve the opprobrium cast on them by some of the nineteenth-century writers. Prometheus, it is said, stole fire from heaven. Fulton bought his in the open market; obtaining his engine in Soho and his boiler in Smithfield he transported them across the Atlantic, and in 1807 produced the _Clermont_. The _Clermont_, a flat-bottomed wall-sided craft 166 feet in length and only 18 feet in beam, steamed at a speed of five knots from New York to Albany, in August, 1807; to the surprise of thousands of spectators who knew her as “Fulton’s folly,” and whose shouts of derision gave place to silence, and then to a chorus of applause and congratulation. Many of the inhabitants of the banks of the Hudson had never heard even of an engine, much less of a steamboat. “A monster moving on the waters, defying the winds and tide, and breathing flames and smoke! The first steamboat used dry pine wood for fuel, which sends forth a column of ignited vapour many feet above the flue, and, whenever the fire is stirred, a galaxy of sparks fly off which, in the night, have a very brilliant and beautiful appearance.”[140] The _Clermont_ was followed by others, each an improvement on the last; until in 1816, so rapid was the process of evolution, the _Chancellor Livingston_ was built, ship-shaped, with figure-head and fine bows, faired sides and tapering stern, with engines of 75-horse-power and with promenade decks and accommodation for 120 passengers. Certain characteristics now showed themselves in all American construction. The engines were mounted with cylinders vertical, their rods actuating large overhead beams which transmitted the force of the steam to the paddlewheels. The boats were made very broad to give the necessary stability, the machinery being carried high; and to reduce their underwater resistance as much as possible their bodies were made full near the water-line and lean below. For the same reason, and since the principal weights were concentrated amidships, fine forward and after bodies were given them; a rising floor, and a deep draught if necessary. The position of the paddlewheels was limited by that of the engine. Experience showed that where two paddles on each side were used their relative position had to be adjusted nicely, otherwise the rear paddles, acting on accelerated water, might actually be a disadvantage. Much difficulty was caused with accidents to paddles; on the Mississippi the wheels were generally mounted astern, where they were protected from floating logs of timber. In some cases double hulls were built, with the paddlewheels between them; but owing to the rush of water on which they acted these wheels were not very efficient.[141] [Illustration: THE _COMET_ OF 1812 From an oil painting in the South Kensington Museum] Fulton had so far built steam vessels only for commercial traffic. He now came near to revolutionizing naval warfare with them. In 1813, in the middle of the war with this country, he presented to the President his plan for a steam-propelled armoured warship for coast defence, a design of an invulnerable vessel of thirty guns, twin-hulled, with a 120-horse-power engine in one hull, a boiler in the other, and a single paddlewheel in a space between the two; double-ended, flat-bottomed, and protected by a belt of solid timber 58 inches thick. Her armament was to consist, in addition to thirty 32-pounders, of submarine guns or columbiads, carried at each end and firing 100-pound projectiles below the water-line. Named the _Demologos_, this monstrous vessel was nearly completed when the war came to an end. It was too late for use. The treaty of Ghent being signed, interest in armaments immediately evaporated. Nevertheless, in the following year a trial of the _Demologos_ was carried out, which showed that a speed of five and a half knots could be attained with her. The _Demologos_, now renamed the _Fulton_, served no useful purpose. She was laid up in Brooklyn Navy Yard, and many years elapsed before steam war vessels were built again in America. § In the meantime progress had been made on this side of the Atlantic. Stimulated by Fulton’s commercial successes, Thomas Bell of Helensburgh built in 1812 a vessel of thirty tons’ burden named the _Comet_, successfully propelled by a 3-horse-power engine which worked a paddlewheel on each beam. This “handsome vessel” was intended to ply between Glasgow and Greenock, to sail by the power of wind, air, and steam; and so it did, with fair financial success, with a square sail triced to the top of a tall smoke-stack: the first passenger steamer to ply in European waters. Shortly afterwards steam vessels were built which pushed out to the open sea. In 1815 the _Argyle_, built on the Clyde and renamed _Thames_ on being purchased by a London company, made a voyage from Greenock to London which was the subject of much comment. On making the Cornish coast after a stormy run south, boats were seen by those on board making towards her with all possible speed in the belief that she was on fire! All the rocks commanding St. Ives were covered with spectators as she entered the harbour, and the aspect of the vessel, we are told, “appeared to occasion as much surprise amongst the inhabitants, as the ships of Captain Cook must have produced on his first appearance among the islands of the South Seas.” Next day the _Thames_, her 9-foot paddlewheels driven by a 16-horse-power engine, reached Plymouth, where the crews of all the vessels in the Sound filled the rigging, and the harbour-master was “struck with astonishment.” From Plymouth she steamed to Portsmouth, making the passage in twenty-three hours. So great was the swarm of vessels that crowded round her, that the port admiral was asked to send a guard to preserve order. She steamed into harbour, with wind and tide, at from twelve to fourteen knots. A court-martial was sitting in the _Gladiator_ frigate, but the whole court except the president adjourned to inspect the strange visitor. Next day the port admiral sent off a guard and band; and soon afterwards he followed, accompanied by three admirals, eighteen post captains, and a large number of ladies.[142] The success of the _Thames_ led to the immediate building of other and larger steamers. In ’17 the son of James Watt purchased a 94-foot boat, the _Caledonia_, fitted her with 28-horse-power machinery driving 10-foot paddlewheels, and for a pleasure trip proceeded in her up the Rhine as far as Coblentz. From this time onwards steam navigation for commercial purposes progressed rapidly. In 1818 a steamboat made regular voyages at sea; the _Rob Roy_, 90 tons, built by Denny of Dumbarton, with engines of 30 horse-power made by Napier, plied regularly between Holyhead and Dublin. In the same year the _Savannah_, a ship of 350 tons’ burden built and fitted with auxiliary steam machinery at New York, crossed the Atlantic, partly under steam; her paddlewheels with their cast-iron frame and axletree successfully withstanding heavy weather. In ’21 the postmaster-general introduced a steam service for the mails at Dover and Holyhead; and in the following year there were steamboats running between London and Leith, and other seaports. The experience of the Holyhead packets was of special value, as it proved that steam vessels could go to sea in weather which would keep sailing vessels in harbour. Soon after this the question was raised of employing steam power to shorten the passage between England and the East, as well as of the navigation by steam of the great Indian rivers. Steam superseded sails in the government mail service between Falmouth, Malta and Corfu; everywhere commercial enterprise was planning new lines of steamships and new possibilities of ocean travel. In ’25 a barque belonging to Mr. Pelham, afterwards Earl of Yarborough, was fitted with steam machinery as an auxiliary and made the voyage to India. The plash of the paddlewheel was then heard for the first time in Oriental waters. By this time the great question of steam as applied to naval ends had arrived to agitate the Admiralty. In ’22 M. Paixhans discharged his revolutionary treatise at the French nation, advocating, with a wealth of argument, a navy of steam-propelled warships armed with a few shell guns. Six years later a warning echo reverberated through Whitehall. Captain Sir John Ross published a volume on “Steam Navigation, with a System of the Naval Tactics peculiar to it,” in which, though his name was not mentioned, the arguments of M. Paixhans were set forth from an opposite point of view. The two books, starting with the same arguments, arrived at diametrically opposite conclusions. While Paixhans claimed that steam power offered important advantages to France, the English writer reached the gratifying conclusion that the change which steam would effect in naval affairs might be rendered favourable to this country. For coast defence alone steam vessels would be invaluable. The colonies would be safer from piracy. Passages, at present difficult or dangerous, would be made with speed and safety. Incidentally, an entirely new system of tactics would be evolved by the coming of steam; each ship-of-the-line would be escorted by a steam vessel, to tow her into position, and concentration of force would be obtained by such means as, harnessing two steamers to one sailing ship, so as to tow one half of the fleet to a position of vantage over the enemy. After the main action the steamers would themselves attack each other; and so on. Both French and English writers agreed that there would be a reversion to the ancient warfare of the galleys; the steamer, whose paddlewheels lent themselves readily to a pivot gun armament and to great powers of manœuvring, would always attack like a bull, facing the enemy, its bows presenting one or more large and well-protected cannon. Sir John Ross regarded the steamer, however, essentially as an auxiliary. M. Paixhans took a more sanguine view. “At this moment,” he wrote in May, ’22, “the English admiralty are building two steam vessels, each of thirty horsepower, one at Portsmouth and one at Plymouth, for tugging sailing ships held up by contrary winds. They commence by being the servitors of the ships-of-the-line; but it is their destiny to become their masters.”[143] But the views of Sir John Ross did not find favour at the Admiralty. In the presence of the revolution the authorities continued to steer a policy of passive resistance to all changes and methods which might have the effect of depreciating existing naval material; and Lord Melville himself penned, as a reply to the Colonial Office to a request for a steam mail service between two Mediterranean ports, the principle which guided the Board. They felt it their bounden duty (he wrote in 1828) to discourage, to the utmost of their ability, the employment of steam vessels, as they considered that the introduction of steam was calculated to strike a fatal blow at the naval supremacy of the Empire.[144][145] So far, then, new methods of propulsion had not been greeted with enthusiasm. Yet to the First Lord himself was due the utilization of steam for minor purposes in the navy. In spite of the non-success of Lord Stanhope’s experimental “ambi-navigator” ship in 1795, Lord Melville in 1815 caused the three-masted schooner _Congo_, designed for a surveying expedition to the river of that name, to be fitted with paddlewheels and machinery by Boulton and Watt, expressly to try it in a ship-of-war. This machinery was so large and ponderous that, not only did it usurp one-third of the space aboard the ship, but brought her down so deep as only to give four knots through the water. It was all removed again before she sailed, and sent to Chatham for use in the dockyard. In the following year we find Mr. Brunel in correspondence with his lordship on the question of steam navigation. Brunel wrote quoting evidence to the effect that paddlewheels could be made of sufficient strength and stiffness to withstand the violence of seas and gales; to which Lord Melville replied that the Board deemed it unnecessary to enter, at that time, into the question of steam navigation generally, but desired his views on the application of steam to the towing of ships-of-war out of harbour against contrary winds and tides: which would be a matter of great advantage to his Majesty’s service. Brunel answered recommending that the steamer _Regent_, plying between Margate and London, be chartered during the winter and employed on this work, as a particular experiment. “From this period may be dated the introduction of steam navigation into the English navy. Lord Melville was now so fully convinced of the great utility which the naval service would derive from it, that he ordered a small vessel to be built at Deptford, by Mr. Oliver Lang, to be called the _Comet_, of the burthen of 238 tons, and to have engines of 80 horse-power. She was built accordingly and ready for sea in 1822.”[146] As a matter of fact, the first steamer actually brought into H.M. service was the _Monkey_, built at Rotherhithe in 1821; and she was followed by the more powerful _Sprightly_, built at Blackwall by Messrs. Wigram and Green in ’23. Gradually the use of these paddlewheel tugs extended, their tonnage and horse-power increased, and the Surveyor of the Navy and his master shipwrights began to divert their talents to a consideration of the small steamers. For the reason stated by Lord Melville, steamers were at this time tolerated only for towing and other subsidiary duties; authority poured cold water on the idea of utilizing them as ships-of-war; and if steam could have been dispensed with altogether, everyone would have been the better pleased. Even at this period the idea of using manual labour, applied in an effective manner, for towing and bringing into position sailing warships had not been altogether abandoned. In 1802 the transport _Doncaster_ had been propelled at a slow speed in Malta harbour by the invention of a Mr. Shorter: a screw propeller rigged over the stern. In 1820 experiments were made at Portsmouth with paddlewheels manually worked, and in ’29 Captain C. Napier took his ship _Galatea_ out of Portsmouth Harbour by use of paddlewheels geared to winches which were worked by the crew. One hundred and thirty men were able to give her a speed of 2½ knots, while the full crew of a hundred and ninety produced a speed of three. After this doubtful success another trial was held--a race between the _Galatea_, propelled by paddles, and the _Briton_, towed by boats--which _Galatea_ won. Captain Napier’s paddlewheels afterwards did good work for his ship in other quarters of the world.[147] Nothing resulted, however, from his initiative in this connection; only was emphasized the enormous superiority of steam-propelled vessels as tugs, in which capacity they had already made their appearance, and from which they were destined to evolve, in the next decade, into fighting vessels of considerable force. By 1830 steam navigation had made significant strides along the lines of commercial development. In that year a service of steam mail boats started to run at regular intervals between Falmouth and Corfu, covering the distance in about one-fourth of the time which had been taken by the sailing packets; a Dutch government steamer, the _Curaçoa_, built in England, had since ’27 been running between Holland and the East Indies; and already the Indian Government had built an armed steamer, designed as the forerunner of others which were to connect Bombay with Suez and thus to place India in more direct communication with England. The navy was still represented only by paddle-tugs. With a change of administration, however, came a change in Admiralty policy. The new Board took a distinctly progressive view. It was agreed that, if foreign powers initiated the building of steam war-vessels, this country must build as well, and not only as well but better: a policy tersely summed up by Admiral Sir T. M. Hardy in his saying, “Happen what will, England must take the lead.” Certain objections to steam vessels as naval units which had hitherto held a vogue were now seen to be ill-founded or baseless. In particular it was discovered, not without surprise to many, that steamers could be manœuvred without difficulty. A paddlewheel steamer, the _Medea_, gained her commander considerable credit from the skill with which she was navigated from the Thames into the basin at Woolwich dockyard, which proved that steamers could be steered and manœuvred better than sailing ships. In ’33 the construction of steamers was placed in the hands of the Surveyor.[148] But small progress was made. One reason alleged was that the shape of hull which the Surveyor had made peculiarly his own was ill-adapted for steam machinery. “Nothing more unpropitious,” observed a later writer, “for Sir William Symond’s mode of construction than the introduction of steam can be conceived. His sharp bottoms were the very worst possible for the reception of engines; his broad beam and short length the most unfavourable qualities that could be devised for steam propulsion. As much as he could, he adhered to his principles.... Rather than yield to the demands of the new power, he sacrificed the armaments of his vessels, kept down the size of their engines, and recklessly exposed the machinery to shot should they go into action.”[149] There doubtless was something in this criticism. And yet, as we have seen, experience in America led to a form of hull for paddle steamers in many respects approaching that condemned as being favoured by the Surveyor! Another and more valid reason for the slow progress made lay in the inherent unsuitability of the paddlewheel steamer as a substitute for the large sailing warship. Not only did the paddlewheels offer a large and vulnerable surface to destruction by enemy shot, but the wheels and their machinery could not be embodied in a ship design without interference with its sails and sailing qualities and, still more, without serious sacrifice of broadside armament. The machinery monopolized a large section of the midship space, the huge wheels covered the sides and interfered with the training of those guns for which room remained. The problem of arming steam-vessels was novel and difficult of solution. The guns must be few and therefore powerful. Hence it appeared that paddlewheel steamers, notwithstanding the advantages they possessed of speed and certainty of motion, could only sustain a small concentrated armament, consisting of the heaviest and most powerful ordnance: guns of large calibre, which possessed large power of offence at ranges where the broadside cannon would be deprived of much of their efficiency. Hence in ’31 a 10-inch shell gun of 84 hundredweight was expressly designed and cast for this purpose; and all the classes of steamers in early use in the navy were armed with it until, in ’41, it was displaced by the 68-pounder pivot gun, which then became the principal pivot gun of the service. Thus the development of paddlewheel machinery reacted on the development of artillery. The steamer was a stimulus to the development of large ordnance worked on the pivot system. And this form of armament in turn influenced the form of the ship. The main weights--those of the propelling machinery--were already concentrated in the waist of the vessel, and it was now possible so to place the few pivot guns that the ends of the vessel were left very lightly loaded. Thus it was possible to give unprecedentedly fine lines to the new steamers, a sharp and lengthened bow and a well-tapered run: an improved form of body by the use of which high speeds were obtained. In the case of commercial steamships the advantages of fine lines had already been recognized, and their designers had been free to give them a form which would allow of a high speed being attained; but in the case of war vessels designed to carry a broadside armament the limitations imposed by the heavily weighted ends had hitherto prevented other than bluff bows and sterns being given them. But now the subject of ship form came under general consideration, and the new conditions led to a more serious study of the laws governing the motion of bodies through water. Year after year the size of steamers grew.[150] And as with size the cost of construction and maintenance increased, the question pressed itself more and more clearly--what was the naval utility of such expensive and lightly armed vessels? Numerous attempts were made to produce a form of paddlewheel steamer which would carry a broadside armament comparable with that which a sailing vessel of the same burthen would bear. In 1843 the _Penelope_, 46 guns, was cut in halves at Chatham and lengthened by the addition of about 65 feet, in which space engines of 650 horse-power were installed. But the extra displacement failed to compensate for the weight of the machinery; the altered vessel drew more water than had been anticipated and, though various alterations were made to minimize the effects of this, the experiment was not a success and was not repeated. In ’45 a steam frigate called the _Odin_ was built by order of the Board. “The results aimed at in constructing this ship were--capability of carrying broadside armament; diminished rolling, in comparison with any war steamers then built; and less draught of water in relation to the size. These objects were accomplished; but as the position of the machinery and boilers is partially above the water-line, and the propellers are exposed to danger in broadside fighting, the ship is necessarily imperfect in these two conditions, as well as in the position of the sails; for in this case the proper place of the mainmast was occupied by the boilers, and consequently the centre of effort of the wind on the sails is in a wrong place.”[151] In the same year the _Sidon_ was laid down, the design being on the lines of the _Odin_ but modified in accordance with the ideas of Sir Charles Napier: with greater depth of hold and with machinery below the water-line. Iron tanks were placed in the hold for carrying the coals; by filling these with water when empty the steamer was kept at a more or less constant draught, a matter of considerable importance to the efficient working of the paddlewheels. In other respects, however, the _Sidon_ was unsatisfactory. She was so crank that the addition of ballast and a modification of her armament were necessary. Her engines were cramped, her boilers of insufficient power and of unsuitable design, and her coal capacity too small to give her a useful radius of action. For the attainment of all the properties specified it was subsequently calculated and shown that a much larger displacement was necessary. Just as Fitch had discovered and Fulton had discerned, increase in scale reduced many of the difficulties encountered in designing heavily weighted steam vessels. Hence the success of the _Terrible_. In the case of the _Terrible_, a large paddlewheel frigate of 1,850 tons and 800 horse-power built in 1845, it was clear that an increase of size had given a partial solution to the problem of designing a war-vessel with heavy and spacious propelling machinery, with adequate armament, and with full sail-power and all the properties of a sailing ship. Still the steam war-vessel was not satisfactory. Her machinery usurped the weight and space required for armament, her cumbrous paddlewheels were far too exposed to damage by shot or shell. And how to surmount these difficulties and reconcile the conflicting requirements of artillery and motive power, was a problem which cost the country years of unsuccessful experiments and millions of money. “It was,” said Dahlgren, “the riddle of the day.” § The problem was solved by the adoption of the screw propeller. Since Archimedes’ day the screw had been known in the form of a pump, and in two familiar objects--the smoke-jack and the windmill--the principle of the driven screw had been for centuries widely employed. In connection with ship propulsion the screw appears to have been tried at an early date, like the Marquis of Worcester’s water-wheel, in the form of a mill. Among the machines and inventions approved by the Royal Academy of Sciences of Paris between the years 1727 and 1731 is one described as a screw, suspended in a framework between two boats, which when acted upon by the current was intended to warp the vessels upstream, the motion of the screw being transmitted to a winch barrel on which a tow-rope was wound. But so far as is known no attempt had been made at this date to use the screw directly as a propeller. In 1768 its use in this form was suggested in a work entitled _Théorie de la Vis d’Archimede_.[152] And shortly after, as we have already seen, Bramah in England and Bushnell in America had patented, and the latter had actually put into use, the screw as a means of propelling vessels through water. We have seen, too, that Fulton successfully adapted the screw propeller, on a small scale, in one of his experimental steamboats. Sporadic attempts were made in the early days of the nineteenth century both in this country and in America to drive ships by means of screws, both manually and by the medium of steam, some of which were attended with a certain measure of success.[153] Yet some time was to elapse before screw propulsion gained recognition. Doubt as to the efficiency of a screw’s action, ignorance as to the shape of the vessel required and as to the best position for the propeller, difficulty in accommodating the early long-stroke steam engine to drive direct an under-water propeller shaft; inertia, prejudice and vested interest, all seem to have played a part in delaying the adoption of what, when it did come, was acknowledged to be the only suitable form of steam propulsion for war vessels. [Illustration: PETTIT SMITH’S PROPELLER] In 1825 a premium was offered by the Admiralty for the best plan of propelling vessels without paddlewheels; and a plan proposed by Commander S. Brown, R.N., was deemed sufficiently promising for trial: a two-bladed screw propeller placed at the bow of a vessel and actuated by a 12-horsepower engine. But though exhibiting advantages this form of the invention did not survive. The history of the screw-propeller may be said to date from 1836. In that year two capable inventors obtained patents: Mr. Francis Pettit Smith and Captain Ericsson. So little attention had, up to that time, been given to the subject that the two proposals “were presented to the public in the character of novelties, and as such they were regarded by the few who had curiosity enough to look at them.” Smith’s patents were for the application of the screw to propel steam vessels by fixing it in a recess or open space formed in the deadwood; and, says Fincham, “the striking and peculiar merit of Mr. Smith’s plan appears to consist, _chiefly_, in his having chosen the right position for it to work in.” Trials were carried out with Smith’s propeller in a 6-ton boat on the City and Paddington canal, and then between Blackwall and Folkestone, with encouraging success; the boat, encountering heavy weather off the Foreland, demonstrated the advantage derived from the absence of paddlewheels, and showed the new form of propelling machinery to place no limitations on her qualities as a sailing vessel. She returned to Blackwall, having run over 400 miles at a mean speed of 8 knots. Captain Ericsson, a Swedish army officer who had come to London and established himself as a civil engineer, had a contemporary success with a boat fitted with two large-bladed propellers each 5 feet 3 inches in diameter. So successful was he, indeed, that he invited the Board of Admiralty to take a trip in tow of his novel craft; a trip which had important and unexpected results on the subsequent progress of steam navigation. One summer day in ’37 the Admiralty barge, in which were the Surveyor and three other members of the Board, was towed by Ericsson’s screw steamer from Somerset House to Limehouse and back at a speed of 10 knots. The demonstration was a complete success, and the inventor anticipated some further patronage of his invention. But to his chagrin nothing was asked of him, and to his amazement he was subsequently informed that the proposal to propel warships by means of a screw had been pronounced impracticable. Never, perhaps, in the whole history of mechanical progress has so signally wrong a decision been made, never has expert opinion been so mistaken. Engineers and shipbuilders all failed to realize the possibilities of the screw. The naval authorities who, in the face of their personal experience, dismissed the project as impracticable (owing to some anticipated difficulties in steering ships fitted with screws) merely expressed the unanimous opinion of the time. “The engineering corps of the empire were arrayed in opposition to it, alleging that it was constructed on erroneous principles, and full of practical defects, and regarding its failure as too certain to authorize any speculations even of its success. The plan was specially submitted to many distinguished engineers, and was publicly discussed in the scientific journals; and there was no one but the inventor who refused to acquiesce in the truth of the numerous demonstrations, proving the vast loss of mechanical power which must attend this proposed substitute for the old-fashioned paddlewheel.”[154] Yet in five years’ time steamers designed for paddlewheels were being converted to carry screws, and a great screw-propelled liner, the _Great Britain_, had been launched for the Atlantic traffic! It was in America, we have seen, that progress in steam navigation was of the greatest interest to the public, and it was by Americans that the disabilities of the paddlewheel were most keenly appreciated. Two witnesses of the trial of Ericsson’s boat saw and admitted the advantages of the new method: Mr. Ogden, an engineer who had been U.S. consul at Liverpool for some years, and Captain Stockton, U.S.N. The latter appreciated the military advantages of screw propulsion and was soon its enthusiastic advocate. Under his influence and encouragement Ericsson threw up his engagements in London and went to America. “We’ll make your name ring on the Delaware,” said Captain Stockton to him at a dinner in his honour given at Greenwich. The prediction was fulfilled. In the course of time Ericsson saw his propeller applied on a large scale, not only to mercantile craft but in the American navy. Early in ’37 Captain Stockton had ordered an iron vessel to be built by Messrs. Laird, of Birkenhead, and fitted with a screw. In the following year she was launched, and in the spring of ’40, after giving demonstration on the Thames of the great towing power of her propeller, she left for America for service as a tug on the big rivers. On this work one of the great advantages of the screw was realized: the immunity with which the screw vessel could work in drift ice, when paddlewheel steamers were perforce laid up. In the meantime, fortunately, Pettit Smith’s successes had not been without their effect on opinion in this country. A company was formed to exploit the screw, and a vessel, the _Archimedes_, was built amid a strange chorus of detraction, opposition and ridicule. She made her trials in October, ’39. Her propeller was at first in the form of a complete convolution of a helical screw of 8-foot pitch and of 5 foot 9 inches diameter; but subsequently this blade was replaced by two, each of which formed half a convolution, with the two halves set at right angles to one another. Comparative trials were ordered by the Admiralty in the following year to test the merits of the _Archimedes’_ screw as compared with the ordinary paddlewheels applied to her Majesty’s mail packets on the Dover station. The results were inconclusive.[155] But a subsequent voyage round the coasts of Great Britain, during which the machinery of the _Archimedes_ was laid open to the inspection of the general public, and a later voyage from Plymouth to Oporto which recreated a new record for a steam passage, went far to establish in public estimation the merits of the new propeller. But generally the invention was discouraged. Prejudice and vested interests, rather than a reasoned conservation, seem to have operated to oppose its progress. “A striking instance of prevailing disinclination to the screw propeller was shown on the issue of a new edition of the _Encyclopædia Britannica_, in which the article on steam navigation contained no notice whatever of the subject.” But in spite of all prepossessions against it the screw had won a decisive victory over its rival. So striking were the results recorded by the _Archimedes_, that a decision was made in December, 1840, to change the _Great Britain_, an Atlantic liner then under construction, from paddlewheel to screw propulsion. In two ways she was a gigantic experiment: she was the first large ship to be built of iron, and it was now proposed to fit her with a screw. Mr. Brunel took all the responsibility for advising the adoption of both these revolutionary features; the result was a splendid testimony to his scientific judgment, boldness of enterprise, and “confident reliance on deductions from facts ascertained on a small scale.” Before the completion of the _Great Britain_ the Admiralty had initiated experiments which were to furnish important information as to the power and efficiency of the screw propeller in its various forms, and to settle beyond cavil the question of its superiority over the paddlewheel for the propulsion of warships. The sloop _Rattler_, 888 tons and 200 horsepower, was fitted with screw machinery. Several forms of screw were tried during the winter of 1843-4. First the screw as used in the _Archimedes_ was fitted: a screw of 9-foot diameter, 11-foot pitch, and of 5½ feet length, consisting of two half-convolutions of a blade upon its axis. Then a screw was tried of the same diameter and pitch but of only 4-foot length; and then the length was again reduced to 3 feet. The effect of cutting down the length was to give an increase of efficiency.[156] The screw was again shortened by 2 feet, and finally to 1 foot 3 inches; with each reduction in length the slip diminished and the propulsive efficiency increased. Various other forms of screws were tried, and it was shown that Pettit Smith’s short two-bladed propeller was on the whole the most efficient. The best form of screw having been determined, it still remained to compare the screw propeller with the paddlewheel. Accordingly the _Alecto_, a paddlewheel sloop of similar lines to the _Rattler_, was selected as the protagonist of the older form of propulsion, while the _Rattler_ herself represented the screw. Naval opinion was still completely divided on the great question, while in the competing sloops the utmost emulation existed, each captain advocating his own type of propeller. The speed trials took place, and showed the _Rattler_ to have an undoubted advantage. The paddlewheel, however, laid claim to a superiority in towing power. So a further competition was ordered, as realistic as any, perhaps, in the history of applied science: nothing less than a tug-of-war between Paddle and Screw, those two contending forms of steam propulsion! Lashed stern to stern and both steaming ahead full power, one evening in the spring of ’45 the two steamers struggled for mastery. And as _Rattler_ slowly but surely pulled over _Alecto_, the question which had been for years so hotly debated was settled; the superiority of the screw was demonstrated. With the adoption of the screw the problem of disposing the armament was settled. The broadsides and the spaces between decks were once more free to the guns along the entire length; moreover the action of the screw was in complete harmony with that of the sails. With the screw as an auxiliary to sail power, and subsequently with the screw as sole means of propulsion, a change came over the character of the pivot armament. Whereas with the paddlewheel the pivot gun was the chief means of offence, when the screw was introduced the broadside was restored, and though the heavy pivot guns were retained (steam and the pivot gun had become associated ideas), yet by their comparatively limited numbers they became a subordinate element in the total armament. [Illustration: _RATTLER_ VERSUS _ALECTO_ From an aquatint in the South Kensington Museum] External affairs now lent a spur to screw propulsion. In ’44 the French navy came under the reforming power of the ambitious Prince de Joinville, and from this year onwards the attitude of France to this country became increasingly hostile and menacing. The thoughts of the French were turned toward their navy. No sooner had de Joinville been placed in command than schemes of invasion were bruited in this country; and the public viewed with some alarm the altered problems of defence imposed on our fleets by the presence in the enemy’s ports of a steam-propelled navy. Sanguine French patriots sought to profit by the advent of the new power. A pamphlet appeared in Paris claiming to prove that the establishment of steam navigation afforded France the very means by which she could regain her former level of naval strength. The writer, using the same arguments as Colonel Paixhans had used in ’22, reviewed the effect of steam power on the rival navies, and pointed to the Duke of Wellington’s warnings in parliament of the defencelessness of the English coasts and to his statement that if Napoleon had possessed steam power he would have achieved invasion. These cries of alarm, said the writer, should trace for France her line of policy. She should emulate the wise development of steam propulsion as practised by Great Britain. “We think, England acts; we discuss theories, she pursues application. She creates with activity a redoubtable steam force and reduces the number of her sailing ships, whose impotence she recognizes.... Sailing vessels have lost their main power; the employment of steamers has reduced them to the subaltern position of the siege artillery in a land army.” The writer praised English policy in the matter of steam development: its wise caution, its reasoned continuity. There had admittedly been some costly deceptions. Nevertheless the method was to be commended, and France should proceed in a similar manner: by a succession of sample units while steam was still in the experimental stage, by far-sighted single strides, and then by bold and rapid construction of a steam navy which would compete on more even terms with that of her hereditary rival.[157] Faced with the probability that our rivals would pursue some such progressive and challenging policy as outlined by the pamphleteer, the Admiralty acted rapidly. Before the _Rattler_ trials were complete a decision was made favourable to the screw propeller, and an order was made for its wide application to warships built and building. It was resolved, on the advice of Sir Charles Napier, that the screw should be regarded solely as an auxiliary to, and in no way as in competition with, sail power. The _Arrogant_ was laid down, the first frigate built for auxiliary steam power; and screws driven by engines of small horse-power were subsequently fitted to other ships with varying degrees of success. Two important features were specified for all: the machinery was required to be wholly below the water-line, and the screw had to be unshippable. Engines were now required for Block Ships and for sea-going vessels. So the principal engineers of the country were called together and were asked to produce engines in accordance with the bare requirements given them. A variety of designs resulted. From the experience obtained with this machinery two important conclusions were quickly drawn: firstly, that gearing might be altogether dispensed with; secondly, that no complex contrivance was necessary for altering the pitch to enable engines to work advantageously under varying conditions, the efficiency of the screw varying very little whether part of the ship’s velocity were due to sail power or whether it were wholly due to the screw.[158] And here it may not be amiss to note, in relation to a nation’s fighting power, the significant position assumed by naval material. In land warfare a rude measure of force could always be obtained by a mere counting of heads. At sea man was in future to act, almost entirely, through the medium of the machine. However we may have deserved the eulogy of the French writer in respect of developing the paddlewheel war steamer, the development of screw propulsion in the next decade was marked by a succession of failures and a large outlay of money on useless conversions and on new construction of poor fighting value, most of which could have been avoided. Had our methods been less tentative and more truly scientific the gain would have been undoubtedly very great; we should have laid our plans on a firmer basis and arrived at our end, full screw power, by a far less circuitous route than that actually taken. In this respect France had the advantage of us. Although a decision had been made to maintain the full sail power of our ships and install screw machinery only as an auxiliary motive power, attempts were naturally made to augment so far as possible the power exerted by the screw; and within a short time new ships were being fitted with machinery of high power, in an endeavour to make the screw a primary means of propulsion. The results were disappointing. As the power increased difficulties thickened. The weight of the machinery grew to be excessive, the economy of the comparatively fast-running and short-stroke engines proved to be low, and the propulsive efficiency of the screws themselves grew unaccountably smaller and smaller. So poor were the results obtained, indeed, that in the case of a certain ship it was demonstrated that, by taking out the high-power machinery and substituting smaller engines an actual gain in speed was obtained, with the reduced displacement. The first screw ship in which an attempt was made to obtain full power with the screw was the _Dauntless_, of 1846. Although a frigate of beautiful lines she was considered a comparative failure. It was agreed that, equipped with paddlewheels and armed with guns of larger calibre, she would have constituted a faster and more powerful warship than, with her 580-horse-power engines, her 10 knots of speed, and her 32-pounder guns, she actually was. Part of the trouble was due to the unsuitability of our ships’ lines for screw propulsion. It has already been noted that, owing to the carriage of heavy weights at their extremities, war vessels were always given very full bows and sterns. In the case of the _Rattler_, whose records served as a criterion for later designs of screw ships, the lines of the stern were unusually fine: partly, no doubt, in imitation of the _Archimedes_. Also, since it had been necessary to allow space enough for a long screw to be carried (a screw of a complete convolution was thought possible) the _Rattler’s_ short screw as finally adopted worked at some distance aft of the deadwood, and thus suffered no retarding influence from it when under way. But in the case of later ships these advantages did not obtain. They were built with the usual “square tuck,” a bluff form of stern which prevented a free flow of water into the space ahead of the propeller and thus detracted from its efficiency. It was not appreciated at this time that, for efficient action, the screw propeller demands to be supplied with a body of unbroken, non-eddying water for it to act upon, which with the square-cut stern is not obtained. At low speeds, and in the ship to which the screw was fitted as an auxiliary, the effect of the square tuck was not marked. But as power and speed increased its effect became more and more evident; the increase in power gave no proportionate increase in speed; and many, ignorant of the cause, surmised that there was a limit to the power which could be transmitted by a screw and that this limit had already been reached. The inefficiency of the square tuck was exposed by trials carried out in H.M.S. _Dwarf_ at Chatham. As a result of these, future new and converted ships were given as fine a stern as possible. For several years, however, the policy of the Admiralty remained the same: the screw was regarded solely as an auxiliary. The French, on the other hand, took a less compromising line of action. After waiting for some time and watching our long series of experiments, they convened in 1849 a grand _Enquête Parliamentaire_: a commission which, primed with the latest information as to British naval material, was to decide on what basis of size, number, armament and means of propulsion future French warships should be built. For two years the commission sat sifting evidence. And then it recommended screw propulsion of the highest power for all new ships, as well as the conversion of some existing classes to auxiliary screw power. England had fitted her ships with screws capable of giving them small speed; France must fit hers with screws of greater power. Speed, said the commission, is an element of power. Superior speed is the only means by which the English can be fought with a good chance of success. Sails must be secondary, therefore, and full reliance must be placed on the screw. The recommendations of the commission were duly realized. In the following years a powerful force of fast screw battleships, frigates, transports, and despatch boats was constructed which by ’58 had brought the aggregate of the horse-power of the French fleet almost to a level with that of England. When the Crimean War brought the two navies together as allies in ’54 the full effect of the new policy of the French had not yet been made apparent. Some apprehension existed in this country as to the adequacy and efficiency of our navy, when compared directly with that of France. But from then onwards this country became aware of the increasing hostility of the French public and government; speeches were made, and letters appeared in the press of both countries, which tended to fan the flames of fear and suspicion.[159] It was not till ’58, however, that general attention was drawn to the great strides which the French navy had made in recent years, and to the skilful way in which its position, relative to that of its great rival, had been improved. An article entitled “The Navies of England and France” appeared in the _Conversations Lexicon_ of Leipsic, and caused a great sensation. Reprinted in book form, with a long analysis and with a mass of information about the French, English and other navies and arsenals,[160] this notorious article brought apprehension to a head. Though written by no friendly critic, it was in most respects an accurate presentment of the respective navies and of their condition. The analysis of Hans Busk, while ostensibly exposing its bias and its inaccuracies, in effect confirmed the main contentions of the German article; in addition his book gave in spectacular columns a summary of the units of the rival navies, which gave food for thought. The article itself professed to show how much France had benefited by the bold and scientific manner in which she had handled the problem of naval construction since the coming of steam. Other factors were discussed, the forms of ships, the Paixhans system of armament, problems of manning and of education; but the factor which had caused the greatest accession of strength to France, by her wise divergence from the English policy, was (according to the critic) steam propulsion. In the case of paddlewheel steamers England, by her unscientific and ruinous experiments, had squandered millions of money and produced a series of crank and inefficient war vessels. In the case of screw ships England’s waste of exertions and money was even more surprising; the building of new ships and the conversion of others was carried out at an enormous cost with many galling disappointments. The French, on the other hand, took longer to consider the principle of the screw, but then, when their more scientific constructors had completed their investigations and analysed the new power, they acted thoroughly and without delay. From all of which the German critic inferred that England had good reason to watch with anxious eye the significant development of strength on the part of her neighbours across the Channel. “We must pronounce,” he concluded, “that with a nearly equal amount of _matériel_, the French navy surpasses the English in capacity and in command of men. France need feel no hesitation in placing herself in comparison with England.... Never was the policy of England so yielding and considerate towards France as at the present day. And then, with respect to the vexed question of the invasion, it is certain that Napoleon III has the means of effecting it with greater ease and far greater chance of success than his uncle.” The means was steam power. But the much-talked-of invasion was never to be attempted. Other events intervened, other developments took place, which reduced the tension between the two great naval powers and removed for an indefinite time the danger, which the Leipsic article disinterestedly pointed out, of war under novel and unprecedentedly terrible conditions: with shell guns and wooden unarmoured steam warships.