Steam from Boiler.
SAVERY’S ENGINE
The marquis had a violent champion in Dr. Desaguliers, who in his Experimental Philosophy, published in 1743, imputed disreputable conduct to the later inventor. “Captain Savery,” said the doctor, “having read the Marquis of Worcester’s book, was the first who put into practice the raising of water by fire. His engine will easily appear to have been taken from the Marquis of Worcester; though Captain Savery denied it, and the better to conceal the matter, bought all the Marquis of Worcester’s books that he could purchase in Pater-Noster Row and elsewhere, and burned them in the presence of the gentleman his friend, who told me this. He said that he found out the power of steam by chance, and invented the following story to persuade people to believe it, viz. that having drunk a flask of Florence at a tavern, and thrown the empty flask upon the fire, he called for a bason of water to wash his hands, and perceiving that the little wine left in the flask had filled the flask with steam, he took the flask by the neck and plunged the mouth of it under the surface of the water in the bason, and the water in the bason was immediately driven up into the flask by the pressure of the air. Now, he never made such an experiment then, nor designedly afterwards, which I shall thus prove,” etc. etc.
Other writers saw no good reason for depriving the captain of the title of inventor. With reference to the book-burning allegation, the only evidence tending to substantiate it lay in the fact that the book “on a sudden became very scarce, and but few copies of it were afterwards seen, and then only in the libraries of the curious.”[74] It has been remarked, also, that Desaguliers was himself to some extent a rival claimant, several improvements, such as the substitution of jet for the original surface condensation being due to him; and that this fact gave a palpable bias to his testimony on the work of others.
In recent years the claims of Savery have been upheld, as against those of the marquis, by a writer who argued, not only that the engine of the marquis had never passed the experimental stage, but that no counter-claim was made by his successors at the time Savery produced his engine and obtained his patent. “Although a patent for ninety-nine years (from 1663 to 1762) was granted the marquis, yet Captain Savery and his successors under his patents which extended for thirty-five years (from 1698 to 1733) compelled every user of Newcomen’s and other steam engines to submit to the most grinding terms and no one attempted to plead that Savery’s patents were invalidated by the Marquis of Worcester’s prior patents.”[75]
By the admirers of Papin it has been claimed that it was from him that Savery received his idea. “After having minutely compared Savery’s machine,” says a biographer of Papin, “one arrives at the conviction that Savery discovered nothing. He had borrowed from Solomon de Caus the use of steam as a motive force, perfected by the addition of a second chamber; from Papin, the condensation of the steam.... And as for the piston, borrowed ten years later by Newcomen, that was wholly Papin’s.”[76]
Suppose it true; even so, his countrymen would always think great credit attaches to Savery for his achievement.
His engine, though used extensively for lifting water through small distances, was exceedingly wasteful of fuel, nor could it be used conveniently for pumping out mines or for other purposes in which a large lift was required. The lift or “head” was directly proportional to the steam pressure. Efforts to improve the lift by augmenting the steam pressure resulted in endless accidents and discouragement; the solder of the engine melted when steam of a higher pressure was used, the joints blew open and the chambers burst.
Living at Dartmouth, within some fifteen miles of Savery’s home, were two men, Newcomen, an ironmonger, and Cawley, a glazier. These two had, doubtless, every opportunity of seeing Savery’s engine at work. They appreciated its limitations and defects, and, undertaking the task of improving it, they so transformed the steam engine that within a short time their design had almost entirely superseded the more primitive form. Here, too, it might be said that they invented nothing. The merit of their new machine consisted in the achievement in practical form of ideas which hitherto had had scarcely more than an academic value. The labours of others gave them valuable aid. Newcomen, it is certain, could claim considerable knowledge of science, and though little is known of his personality there is evidence that he had pursued for years the object which he now achieved. He knew of the previous forms of piston engine which had been invented. He had probably read a translation, published in the Philosophical Transactions, of Papin’s proposal for an atmospheric engine with a vacuum produced by the condensation of steam. He obtained from Savery the idea of a separate boiler, and other details. And where Papin had failed, Newcomen and his partner succeeded. Their Atmospheric Steam Engine, as it was aptly called, was produced in the year 1705, and at once proved its superiority over the old “Miner’s Friend.” It had assumed an entirely new form. In a large-bore vertical cylinder a brass piston was fitted, with a leather flap round its edge and a layer of water standing on it to form a seal against the passage of steam or air. The top of the cylinder was open to the atmosphere, the bottom was connected by a pipe with a spherical boiler. The piston was suspended by a chain to one end of an overhanging timber beam, which was mounted on a brick structure so as to be capable of oscillating on a gudgeon or axis at its middle. One end of this beam was vertically over the piston; at the other end was the bucket of a water-pump, also attached to a crosspiece or “horse-head,” by means of a chain or rod. The whole machine formed a huge structure like a pair of scales, one of which (the water-pump) was loaded with weights so as to be slightly heavier than the other (the steam engine).