Sir Harry Lauder

Power from Steam

James Watt,
page 5 of 12

was Dr. Dionysius Papin, a Frenchman, who took refuge in London after the Revocation of the Edict of Nantes. To him we owe the well-known Papin Digester, and the invention of the safety valve. Dr. Smiles states, “He discovered that if the vapour of boiling water could be prevented escaping, the temperature of the boiling water could be raised much above boiling point: and it occurred to him to employ this increased heat in more effectually extracting the nutritious matter from the bones of animals before 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 vessel bursting from internal pressure, he was led to the invention of the safety valve, which consisted of a small movable plate, 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 steelyard. 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.” He was also the first to construct a model steamboat. After fifteen years’ labour he managed to fit a model engine in a boat of which he wrote, “This, by means of fire, will render one or two men capable of producing more effect than some hundreds of rowers.” He proceeded to bring the little vessel from Marburg to London, and it actually reached Münden, when, to his great grief, it was seized by the boatmen on the river and destroyed.

The first in England to manufacture steam engines was Thomas Savery, a military engineer. He was also the first to think of moving a vessel by paddle-wheels, worked by a capstan in the centre of the boat. He was led to make the invention through the difficulty which had been experienced in getting ships in motion, so as to place them alongside the enemy in sea fights, especially difficult in calm weather. Strange that though he knew the principle of the steam engine, he did not think of working the paddles by means of it. His engine was designed principally for the pumping of water from mines. In Cornwall the mines had been wrought out near the surface. As the men went deeper, they were drowned out. He contrived an engine for the purpose of raising the water. It was cumbrous and liable to get out of order and become useless. It was both dangerous and unmanageable, and did not come into general use.

Thomas Newcomen, a blacksmith and ironmonger in Dartmouth, was the next who improved the fire-engine. Taking advantage of Papin’s and Savery’s discoveries, he contrived a steam engine which has been thus described by Dr. Smiles: “The steam was generated in a separate boiler, as in Savery’s, from which it was conveyed into a vertical cylinder underneath a piston fitting it closely, but movable, upwards and downwards, through its whole length. The piston was fixed to a rod which was attached by a joint or chain of a lever vibrating on its own axis, the other end being attached to a rod working a pump. When the piston in the cylinder was raised, steam was let into the vacated space through a tube fitted into the top of the boiler, and mounted with a stop-cock. The pump rod at the further end of the lever being thus depressed, cold water was applied to the sides of the cylinder; on which the steam within it was as condensed, a vacuum was produced, and the external air pressing upon the top of the piston forced it down into the empty cylinder. The pump rod was thereby raised, and the operation of depressing and raising it being repeated, a


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