Notwithstanding his rebuff by the Navy Surveyor, Savery proceeded to fit up a small yacht with his engine, and tried an experiment with it on the Thames, in sight of many thousands of spectators. The experiment was, in his opinion, entirely successful. The yacht, manned by eight sailors working the capstan, passed a ketch with all its sails spread, as well as other vessels. “All people,” said Savery, “seemed to like the demonstration of the use of my engine, the public newspapers speaking very largely of it, yet all to no purpose.” Savery had already expended 200l. in his experiments on the paddle-wheel boat, and was not disposed to go any further, now that Government had decided not to take up the invention. Indeed, its practical utility was doubtful. The power of the wind was, after all, better than hand-labour for working large ships; and it continued to maintain its superiority until the steam-engine was brought to perfection.
It is curious that it should not have occurred to Savery, who invented both a paddle-wheel boat and a steam-engine, to combine the two in one machine; but he was probably sick of the former invention, which had given him so much vexation and annoyance, and gave it up in disgust, leaving it to Papin, who saw both his inventions at work, to hit upon the grand idea of combining the two in a steam-vessel,—the only machine capable of effectually and satisfactorily rowing ships in a calm, or against wind and tide.
It is probable that Savery was led to enter upon his next and most important invention by the circumstance of his having been brought up in the neighbourhood of the mining districts, and being well aware of the great difficulty experienced by the miners in keeping their pits clear of water, to enable them to proceed with their underground operations. The early tin-mining of Cornwall was for the most part what was called “stream-work,” being confined mainly to washing and collecting the diluvial deposits of the ore. Mines usually grew out of these stream-works; the ground was laid open at the back of the lodes, and the ore was dug out as from a quarry. Some of these old openings, called “coffins,” are still to be met with in different parts of Cornwall. The miners did not venture much below the surface, for fear of the water, by which they were constantly liable to be drowned out. But as the upper strata became exhausted, they were tempted to go deeper in search of the richer ores. Shafts were sunk to the lodes, and they were followed underground. Then it was that the difficulty of water had to be encountered and overcome; for unless it could be got rid of, the deeper ores of Cornwall were as so much buried treasure. When the mines were of no great depth, it was possible to bale out the water by hand-buckets. But this expedient was soon exhausted; and the power of horses was then employed to draw the buckets. Where the lodes ran along a hill-side, it was possible, by driving an adit from a lower point, to let off the water by natural drainage. But this was not often found practicable, and in most cases it had to be raised directly from the shafts by artificial methods. As the quantity increased, a whim or gin moving on a perpendicular axis was employed to draw the water.[25] An improvement on this was the rack and chain pump, consisting of an endless iron chain mounted with knobs of cloth stiffened with leather, inclosed in a wooden pump of from six to eight inches bore, the lower part of which rested in the well of the mine. The chain was turned round by a wheel two or three feet in diameter, usually worked by men, and the knobs with which it was mounted brought up a stream of water according to the dimensions of the pump. Another method, considered the most effectual of all, was known as “the water-wheel and bobs,” consisting of a powerful pump, or series of pumps, worked by a water-wheel. But although there is no want of water underground in Cornwall, and no want of rain above ground, there are few or no great water-courses capable of driving machinery; besides, as the mines are for the most part situated on high ground, it will be obvious that water-power was available to only a very limited extent for this purpose.
It is also worthy of notice that the early mining of Cornwall was carried on by men of small capital, principally by working men, who were unable to expend any large amount of money in forming artificial reservoirs, or in erecting the powerful pumping machinery necessary for keeping the deeper mines clear of water. The Cornish miners, like the Whitstable oyster-dredgers, worked upon the principle of co-operation. This doctrine, now taught as a modern one, was practised by them almost time out of mind. The owner of the land gave the use of his land, the adventurers gave their money, and the miners their labour; all sharing in the proceeds according to ancient custom. For the use of his land, and for the ore taken from the mine, the lord usually took a sixth part; but in consideration of draining the mine, and in order to encourage the adventure, he was often content with an eighth, or it might be only a tenth part of the produce. The miners, on their part, agreed to divide in the proportions in which they took part in the work. Their shares of the ore raised were measured by barrows, and parcelled into heaps; “and it is surprising,” says Borlase, “to see how ready and exact the reckoners are in dividing, though oftentimes they can neither write nor read. The parcels being laid forth, lots are cast, and then every parcel has a distinct mark laid on it with one, two, or three stones, and sometimes a bit of stick or turf stuck up in the middle or side of the pile; and when these marks are laid on, the parcels may continue there half a year or more unmolested.”[26]
These were, however, the early and primitive days of mining, when the operations were carried on comparatively near the surface, and the capital invested in pumping-machinery was comparatively small in amount. As the miners went deeper and deeper into the ground, and the richer lodes were struck and followed, the character of mining became considerably changed. Larger capitals were required to sink the shafts and keep them clear of water until the ore was reached; and a new class of men, outside the mining districts, was induced to venture their money in the mines as a speculation. Yet the system above described, though greatly modified by altered circumstances, continues to this day; and the mining of Cornwall continues to be carried on mainly upon the co-operative or joint-stock system.
When the surface lodes became exhausted, the necessity of employing some more efficient method of pumping the water became more and more urgent. In one pit after another the miners were being drowned out, and the operations of an important branch of national industry were in danger of being brought to a complete standstill. It was under these circumstances that Captain Savery turned his attention to the contrivance of a more powerful engine for the raising of water; and after various experiments, he became persuaded that the most effective agency for the purpose was the power of steam. It is very probable that he was aware of the attempts that had been previously made in the same direction, and he may have gathered many useful and suggestive hints from the Marquis of Worcester’s ‘Century;’ but as that book contained no plans nor precise definitions of the methods by which the Marquis had accomplished his objects, it could have helped him but little towards the contrivance of a practicable working engine.[27]
How Savery was led to the study of the power of steam has been differently stated. Desaguliers says his own account was this,—that having drunk a flask of Florence at a tavern, and thrown the empty flask on the fire, he called for a basin of water to wash his hands, and perceiving that the little wine left in the flask had changed to steam, he took the vessel by the neck and plunged its mouth into the water in the basin, when, the steam being condensed, the water was immediately driven up into the flask by the pressure of the atmosphere. Desaguliers disbelieved this account, but admits that Savery made many experiments upon the powers of steam, and eventually succeeded in making several engines “which raised water very well.” Switzer, who was on intimate terms with Savery, gives another account. He says the first hint from which he took the engine was from a tobacco-pipe, which he immersed in water to wash or cool it; when he discovered by the rarefaction of the air in the tube by the heat or steam, and the gravitation or pressure of the exterior air on the condensation of the latter, that the water was made to spring through the tube of the pipe in a most surprising manner;[28] and that this phenomenon induced him to search for the rationale, and to prosecute a series of experiments which issued in the invention of his fire-engine.
However Savery may have obtained his first idea of the expansion and condensation of steam, and of atmospheric pressure, it is certain that the subject occupied his attention for many years. He had the usual difficulties to encounter in dealing with a wholly new and untried power, in contriving the novel mechanism through which it was to work, and of getting his contrivances executed by the hands of mechanics necessarily unaccustomed to such kind of work. “Though I was obliged,” he says, “to encounter the oddest and almost insuperable difficulties, I spared neither time, pains, nor money, till I had absolutely conquered them.”
Having sufficiently matured his design, he had a model of his new “Fire Engine,” as he termed it, made for exhibition before the King at Hampton Court in 1698. William III., who was himself of a mechanical turn, was highly pleased with the ingenuity displayed in Savery’s engine, as well as with its efficient action, and he permitted the inventor to dedicate to him ‘The Miner’s Friend,’ containing the first published description of his invention. The King also promoted Savery’s application for a Patent, which was secured in July, 1698,[29] and an Act confirming it was passed in the following year.
Savery’s next step was to bring his invention under the notice of the Royal Society, whose opinion on all matters of science was listened to with profound respect. He accordingly exhibited his model at a meeting held on the 14th of June, 1699, and it is recorded in the minutes of that date, that “Mr. Savery entertained the Society with showing his engine to raise water by the force of fire. He was thanked for showing the experiment, which succeeded according to expectation, and was approved of.” The inventor presented the Society with a drawing of his engine, accompanied by a description, which was printed in the ‘Transactions.’[30]