By omitting the principle of condensation, this machine loses 26 feet in the perpendicular lift. But, indeed, in every point of view, it is inferior to the engines of Savery and Newcomen.
(45.) From the construction of the atmospheric engine by Newcomen, in 1705, for about half a century, no very important step had been made in the improvement of the steam engine. During this time the celebrated Smeaton had given much attention to the details of the atmospheric engine, and brought that machine to as high a state of perfection as its principle seemed to admit, and as it has ever since reached.
In the year 1763, JAMES WATT, a name illustrious in the history of mechanical science, commenced his experiments on steam. He was born at Greenock, in the year 1736; and at the age of 16 was apprenticed to a mathematical instrument-maker, with whom he spent four years. At the age of 20 he removed to London, where he still pursued the same trade under a mathematical instrument-maker in that city. After a short time, however, finding his health declining, he returned to Scotland, and commenced business on his own account at Glasgow. In 1757 he was appointed mathematical instrument-maker to the university of Glasgow, where he resided and carried on business.
This circumstance produced an acquaintance between him and the celebrated Dr. Robison, then a student in Glasgow, who directed Watt's attention to the steam engine. In his first experiments he used steam of a high-pressure; but found it attended with so much danger of bursting the boiler, and difficulty of keeping the joints tight, and other objections, that he relinquished the inquiry at that time.
(46.) In the winter of 1763, Watt was employed to repair the model of an atmospheric engine, belonging to the natural philosophy class in the university--a circumstance which again turned his attention to the subject of the steam engine. He found the consumption of steam in working this model so great, that he inferred that the quantity wasted, must have had a very large proportion to that used in working the piston. His first conclusion was, that the material of the cylinder (brass) was too good a conductor of heat, and that much was thereby lost. He made some experiments, accordingly, with wooden cylinders, soaked in linseed oil, which, however, he soon laid aside. Further consideration convinced him that a prodigious waste of steam was essential to the very principle of the atmospheric engine. This will be easily understood.