[By R. P. Leitch.]
The uses to which Savery proposed to apply his engine were various. One was to pump water into a reservoir, from which, by falling on a water-wheel, it might produce a continuous rotary motion. Another was to raise water into cisterns for the supply of gentlemen’s houses, and for use in fountains and as an extinguisher in case of fire. A third was to raise water for the supply of towns, and a fourth to drain fens and marsh lands. But the most important, in the inventor’s estimation, was its employment in clearing drowned mines and coal-pits of water. He showed how water might be raised from deep mines by using several engines, placed at different depths, one over the other. Thus by three lifts, each of 80 feet, water might be raised from a mine about 240 feet—then considered a very great depth. From Savery’s own account, it is evident that several of his engines were erected in Cornwall; and it is said that the first was tried at Huel Vor, or “The Great Work in Breage,” a few miles from Helstone, then considered the richest tin mine in the county. The engine was found to be an improvement on the methods formerly employed for draining the mine, and sent the miners to considerably greater depths. But the great pressure of steam required to force up a high column of water was such as to strain to the utmost the imperfect boilers and receivers of those early days; and the frequent explosions which attended its use eventually led to its discontinuance in favour of the superior engine of Newcomen, which was shortly after invented.
Savery also endeavoured to introduce his engine in the coal-mining districts, but without success, and for the same reason. The demand for coal in connection with the iron manufacture having greatly increased in the county of Stafford, and the coal which lay nearest the surface having been for the most part “won,” the mining interest became very desirous of obtaining some more efficient means of clearing the pits of water, in order to send the miners deeper into the ground. Windlass and buckets, wind-mills, horse-gins, rack-and-chain pumps, adits, and all sorts of contrivances had been tried, and the limit of their powers had been reached. The pits were fast becoming drowned out, and the ironmasters began to fear lest their manufacture should become lost through want of fuel. Under these circumstances they were ready to hail the invention of Captain Savery, which promised to relieve them of their difficulty. He was accordingly invited to erect one of his engines over a coal-mine at the Broadwaters, near Wednesbury. The influx of water, however, proved too much for the engine; the springs were so many and so strong, that all the means which Savery could employ failed to clear the mine of water. To increase the forcing power he increased the pressure of steam; but neither boiler nor receiver could endure it, and the steam “tore the engine to pieces; so that, after much time, labour, and expense, Mr. Savery gave up the undertaking, and the engine was laid aside as useless.”[34]
He was no more successful with the engine which he erected at York-buildings to pump water from the Thames for the supply of the western parts of London. Bradley says that to increase its power he doubled every part, but “it was liable to so many disorders, if a single mistake happened in the working of it, that at length it was looked upon as a useless piece of work, and rejected.”[35] Savery’s later engines thus lost him much of the credit which he had gained by those of an earlier and simpler construction. It became clear that their application was very limited. They involved much waste of fuel through the condensation of the hot steam pressing upon the surface of the cold water, previous to the expulsion of the latter from the vessel; and eventually their use was confined to the pumping of water for fountains and the supply of gentlemen’s houses, and in some cases to the raising of water for the purpose of working an overshot water-wheel. Various attempts were made to improve the engine by Bradley, by Papin, by Desaguliers, and others; but no great advance was made in its construction and method of working until it was taken in hand by Newcomen and Calley, whose conjoint invention marks an important epoch in the history of the steam-engine.
Not much is known of the later years of Savery’s life. We find him a Captain of Military Engineers in 1702;[36] and in 1705, with the view of advancing knowledge in his special branch of military science, he gave to the world a translation, in folio, of Cohorn’s celebrated work on fortification. The book was dedicated to Prince George of Denmark, to whom he was indebted, in the same year, for his appointment to the office of Treasurer of the Hospital for Sick and Wounded Seamen. Various letters and documents are still to be found in the Transport Office, Somerset House, addressed to him in that capacity.[37] In 1714 he was further indebted to Prince George for the appointment of Surveyor to the Waterworks at Hampton Court; but he did not live to enjoy it, as he died in the course of the following year. He is said to have accumulated considerable property, which he bequeathed to his wife, together with all interest in his inventions. His will was executed on the day of his death, the 15th of May, 1715, and was proved four days after in the Prerogative Court of Canterbury. He there described himself as “of the parish of Saint Margaret, at Westminster, Esquire.” His widow herself died before all his effects were administered. There was a considerable amount of unclaimed stock, which the Savery family were prevented from claiming, as it had passed to the widow; and it has since been transferred to the credit of the National Debt.
CHAPTER IV.
Thomas Newcomen—The Atmospheric Engine.
The invention of the steam-engine had advanced thus far with halting steps. A new power had been discovered, but it was so dangerous and unmanageable that it was still doubtful whether it could be applied to any useful purpose. What was still wanting was an engine strong enough to resist the internal pressure of highly-heated steam, and so constructed as to work safely, continuously, and economically. Many attempts had been made to contrive such a machine; but, as we have shown, the results were comparatively barren. Savery’s small engine could raise water in moderate quantities to limited heights; but the pumping of deep mines was beyond its power. It could force water to a height of about sixteen fathoms; but as the depth of mines at that time was from fifty to a hundred yards, it was obviously incompetent for their drainage. It is true, Savery proposed to overcome the difficulty by erecting a series of engines, placed one over another in the shaft of the mine; but the expense of their attendants, the great consumption of fuel, the cost of wear and tear, the constant danger of explosion, and the risk of the works being stopped by any one of the engines becoming temporarily deranged, rendered it clear that the use of his engine for ordinary mining purposes was altogether impracticable.
Such was the state of affairs when Thomas Newcomen of Dartmouth took up the subject. Comparatively little is known of the personal history of this ingenious man. Mechanical inventors excited little notice in those days; they were looked upon as schemers, and oftener regarded as objects of suspicion than of respect. Thomas Newcomen was by trade an ironmonger and a blacksmith. The house in which he lived and worked stood, until quite recently, in Lower Street, Dartmouth. Like many of the ancient timber houses of that quaint old town, it was a building of singularly picturesque appearance. Lower Street is very narrow; the houses in it are tall and irregular, with overhanging peaked gable-ends. A few years since, Newcomen’s house began to show indications of decay; the timber supports were fast failing; and for safety’s sake it was determined to pull it to the ground.
