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.)]

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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.

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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 s