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.