DIONYSIUS PAPIN, M.D., F.R.S.
The next prominent experimenter on the powers of steam was Dr. Dionysius Papin. He was born at Blois about the middle of the seventeenth century, and educated to the profession of medicine. After taking his degree at Paris, he turned his attention more particularly to the study of physics, which soon occupied his whole attention; and under the celebrated Huyghens, then resident in that city, he made rapid progress. He would, doubtless, have risen to great distinction in his own country, but for the circumstance of his being a Protestant. To escape the persecutions to which all members of that persuasion were then subject, Papin fled from France in 1681, together with thousands of his countrymen, a few years before the Revocation of the Edict of Nantes. He took refuge in London, where he was welcomed by men of science, and more especially by the celebrated Boyle, under whose auspices he was introduced to the Royal Society, of which he was appointed Curator at an annual salary.
It formed part of Papin's duty, in connection with his new office, to produce an experiment at each meeting of the Society. He was thus induced to prosecute the study of physical science; and in order to stimulate the interest of the members, he sought to introduce new subjects from time to time to their notice. One of the greatest novelties of his "entertainments" was the production of his well-known Digester, which excited a considerable degree of interest; and on one occasion a philosophical supper, cooked by the Digester, was served up to the Fellows, of which Evelyn gives an amusing account in his Diary.
He was led to the invention of the Digester by certain experiments which he made for Boyle. He discovered that if the vapour of boiling water could be prevented escaping, the temperature of the water would be raised much above the boiling point; and it occurred to him to employ this increased heat in more effectually extracting nutritious matter from the bones of animals, until then thrown away as useless. The great strength required for his Digester, and the means he was obliged to adopt for the purpose of securely confining the cover, must have early shown him what a powerful agent he was experimenting on. To prevent the bursting of the vessel from the internal pressure, he was led to the invention of the safety-valve, which consisted of a small moveable plate, or cylinder, fitted into an opening in the cover of the boiler, and kept shut by a lever loaded with a weight, capable of sliding along it in the manner of a steel yard. The pressure of the weight upon the valve could thus be regulated at pleasure. When the pressure became so great as to endanger the safety of the boiler, the valve was forced up, and so permitted the steam to escape. Although Papin was thus the inventor of the safety-valve, it is a curious fact that he did not apply it to the steam-machine which he subsequently invented, but adopted another expedient.
The reputation of Papin having extended to Germany, he was, in 1687, invited to fill the office of Professor of Mathematics in the University of Marburg, and accepted the appointment. He continued, however, to maintain a friendly correspondence with his scientific friends in England, and communicated to the Royal Society the results of the experiments in physics which he continued to pursue. In the same year in which he settled at Marburg, he submitted to the Society an important paper, which indicated the direction in which his thoughts were then running. It had occurred to him, as it had before done to Hautefeuille, that the explosion of gunpowder presented a ready means of producing a power to elevate a piston in a tube or cylinder, and that, when so raised, a vacuum could be formed under the piston by condensing the vapour, and so ensuring its return by the pressure of the atmosphere. He thought that he might thus be enabled to secure an efficient moving force. But it was found in practice, that the proposed power was too violent as well as uncertain, and it was shortly given up as impracticable.
Papin next inquired whether his proposed elastic force and subsequent vacuum might not better be produced by means of steam. He accordingly entered upon a series of experiments, which gradually led him to the important conclusions published in his celebrated paper on "A New Method of Obtaining very Great Moving Powers at Small Cost," which appeared in the 'Acta Eruditorum' of Leipsic, in 1690. "I felt confident," he there observes, "that machines might be constructed wherein water, by means of no very intense heat, and at small cost, might produce that perfect vacuum which had failed to be obtained by means of gunpowder." He accordingly contrived a machine to illustrate this idea, but it was very imperfect and slow in its action, as may well be imagined from the circumstance that to produce the condensation he did not apply cold, but merely took away the fire! Still he was successfully working out, step by step, the important problem of steam power. He clearly perceived that a piston might be raised in a cylinder by the elastic force of steam, and that on the production of a vacuum by its condensation, the piston might be driven home again by the pressure of the atmosphere. The question was, how was this idea to be realised in a practicable working machine? After many experiments, Papin had the courage to make the attempt to pump water by atmospheric pressure on a large scale. He was employed to erect machines after his principle, for the purpose of draining mines in Auvergne and Westphalia; but from the difficulty he experienced in procuring and preserving a vacuum, and the tediousness of the process, his enterprise proved abortive.
The truth is, that fertile though Papin was in conception, he laboured under the greatest possible disadvantage in not being a mechanic. The eyes and hands of others are not to be relied on in the execution of new and untried machines. Unless eyes and hands be disciplined by experience in skilled work, and inspired by intelligence, they are comparatively useless. The chances of success are vastly greater when mind, eyes, and hands, are combined in one person. Hence the unquestionable fact that though the motive power of steam had long been the subject of ingenious speculation and elaborate experiment amongst scientific men, it failed to be adopted as a practicable working power until it was taken in hand by mechanics-by such men as Newcomen, the blacksmith; Potter, the engine-driver; Brindley, the millwright; and, above all, by James Watt, the mathematical instrument maker.
The sagacious foresight of Papin as to the extensive applicability of steam-power as a motive agent, is strikingly shown by the following passage in the paper above referred to:-"If any one," says he, "will consider the magnitude of the forces to be obtained in this way (i. e., by the atmospheric high-pressure engine he was suggesting), and the trifling expense at which a sufficient quantity of fuel can be procured, he will certainly admit that this very method is far preferable to the use of gunpowder above spoken of, especially as in this way a perfect vacuum is obtained, and so the inconveniences above recounted are avoided. In what manner that power can be applied to draw water or ore from mines, to discharge iron bullets to a great distance, to propel ships against the wind, and to a multitude of other similar purposes, it would be too long here to detail; but each individual, according to the particular occasion, must select the construction of machinery appropriate to his purpose." This last was, however, the real difficulty to be overcome. Steam, doubtless, contained a power to do all these things; but as for the machine that would work quietly, docilely, and effectively, in pumping water, discharging bullets, or propelling ships, the mechanic had not yet appeared that was able to make one.
Papin was, however, a man of great perseverance; and, strong in his faith as to the power of steam to propel ships, he gradually worked his way to the contrivance of a model steamboat. When in London, he had seen an experiment tried by the Prince Palatine Rupert on the Thames, in which a boat fitted with revolving paddles attached to the two ends of an axle which received its motion from a trundle working on a wheel turned round by horses, went with such rapidity as to leave the king's barge, manned by sixteen rowers, far behind in the race. The idea which occurred to Papin was, to apply a steam machine to drive the paddles, and thus ensure a ship's motion independent of wind or tide. For this purpose, it was necessary to convert the alternate motion of the piston-rod into a continuous rotary one; and this he proposed to effect "by having the rods of the pistons fitted with teeth, which would force round small wheels, toothed in like manner, fastened to the axis of the paddles."
ANCIENT PADDLE-BOAT.
The use of paddle-wheels in propelling boats had long been known. The Harleian MSS. contain an Italian book of sketches, attributed to the fifteenth century, in which there appears the annexed sketch of a paddle-boat. This boat was evidently intended to be worked by two men turning the crank by which the paddles were made to revolve. There were many other early schemes of paddle-boats, some of which were proposed to be worked by horse-power. The name of Blasco Garay has often been mentioned as the first who applied the power of steam to the driving of paddle-boats; but for this there is not the slightest foundation. M. Bergenroth informs us that he has carefully examined all the documents relating to the trials of Blasco Garay in the archives at Simancas, but has found no reference whatever to steam as...
