386 



STEAM ENGINE. 



pump rods. Another condensation by the injection 

 of cold water would cause the piston to descend, 

 and so the alternate rising and fulling ot the piston 

 and pump rods was continued. The steam and cold 

 \v;ittT were admitted, at the proper intervals of 

 time, by an attendant, who turned stop cocks. It 

 is recorded that a boy, named Potter, contrived, by 

 attaching cords and cut dies to the beam and cocks, 

 to cause the engine to admit and cut off the steam 

 and the cold wafcer at proper intervals. This oc- 

 curred about the year 1712, but in 1717, Mr Henry 

 Beighton, of Newcastle-upon-Tyne, made a more 

 complete and effective arrangement for opening and 

 shutting the valves. In the year 1720, one Leupold, 

 a German, made the first proposal of a high pressure 

 engine. He placed two cylinders above the boiler, 

 the cylinders being placed side by side, and furnished 

 with pistons. At the bottom of each cylinder an 

 opening was made into a cavity, in which a four 

 way cock was placed, so constructed that when a 

 free passage was opened between the bottom of one 

 cylinder and the boiler, a free passage was opened 

 at the same instant between the bottom of the other 

 cylinder and the atmosphere. Steam of an elastic 

 force greater than the atmospheric pressure, was 

 generated in the boiler, and being admitted into the 

 bottom of one of the cylinders, forced up the piston 

 to the top, while at the same time a free communi- 

 cation was opened between the bottom of the other 

 cylinder, which allowed the steam it contained to 

 make a free escape and the piston to descend. The 

 four way cock was now turned so as to permit the 

 steam in the cylinder whose piston was up,to escape, 

 and therefore the piston would descend, while the 

 other piston would be forced up by the steam from 

 the boiler being admitted below it ; and thus the 

 operation was continued. About 1757, Fitzgerald 

 proposed the use of the fly wheel, a simple yet power- 

 ful augmentation to the efficacy of the steam engine 

 as a mover of machinery. The celebrated Smeaton 

 did a great deal to improve the construction of 

 Newcomen's engines, and his labours contributed 

 in no small degree to hasten the engine to that state 

 of perfection in which we now find it. JohnBlakey 

 took out a patent, in 1766, for a proposed improve- 

 ment on Savary's engine, in which he used two re- 

 ceivers, one placed above the other, preventing the 

 contact of the steam and water by a floating stratum 

 of oil, but his contrivance was impracticable. He 

 had, however, the merit of inventing tubulated 

 boilers, now so extensively employed in locomotive 

 engines. 



The greatest improvements ever yet made on 

 the steam engine were reserved for Dr James Watt, 

 a native of Greenock, but at the time his attention 

 was drawn to the subject, a mathematical instru- 

 ment maker in Glasgow. He began his researches 

 on the nature of steam as early as 1763, but his 

 plans for improving the steam engine seem not to 

 have been matured until about 1768, and in the year 

 following he obtained his first patent for " Methods 

 of lessening the consumption of Steam, and conse- 

 quently of fuel in fire engines." The great improve- 

 ment held forth in the specification consists in con- 

 densing the steam, not in the steam cylinder, but in 

 a separate vessel, with which it was made to com- 

 municate occasionally by the opening and shutting 

 of a valve. By this means the steam cylinder was 

 not copied down by the injection of cold water at 

 every condensation, as in the engine of Newcomen, 

 otherwise called the atmospheric engine, and all the 

 steam which was expended in heating the cylinder j 



in Newcomen's engine was thus saved. He alsa 

 specified his method of extracting the air and water 

 from the condenser, by means of pumps, and like- 

 wise the employment of high pressure, or what he 

 terms expansive, steam to work the engine, either 

 with or without condensation. Watt might thus 

 be considered the inventor of the high pressure en- 

 gine, but the priority is due to Leupold, who pro- 

 posed an engine with two cylinders on the high 

 pressure principle. In the same specification he 

 also includes the rotatory engine to be applied to 

 the turning of mills. Instead of rendering the pis- 

 ton air-tight by water on its upper surface, he pro- 

 poses oil, wax, mercury, &c. In 1781, one Steed 

 obtained a patent for the crank motion, in order to 

 convert the alternating motion of the beam into a 

 continuous rotatory motion ; but there is strong 

 proof that the invention was stolen from Watt, as 

 a pattern of the crank was lying in the yard of 

 Boulton and Watt's foundery, at Soho, for some 

 time previous to the date of Steed's patent. (See 

 Life of James Watt, Chambers' Biography of Emin- 

 ent Scotsmen.) Watt was thus driven to the inven- 

 tion of that beautiful motion, the sun and planet 

 wheel, as a substitute for the crank, for which he 

 obtained a patent the same year. Mr Jonathan 

 Hornblower took out a patent, in 1781, for an in- 

 genious method of employing steam so as to act ex- 

 pansively. He employed two cylinders.; first al- 

 lowing the steam to act uniformly in one, and then 

 to act by expansion in the other ; but as he could 

 not employ a separate condenser he could not bring 

 his engine into use. This was compensated for by 

 Watt, who, in the year following, i. e. 1782, took 

 out letters patent for his expansive engine. He 

 employed only one cylinder, and effected the action 

 from expansion, by admitting high pressure steam 

 at the beginning of the stroke, but cutting it off 

 when the piston had moved a certain space, after 

 which the steam expanded to the end of the stroke. 

 It is but justice to add, that Watt had employed 

 the expansive engine both at Soho and Shadwell, 

 between the years 1776 and 1778. In the patent 

 of 1782, Watt included many contrivances for re- 

 gulating the power of the double-acting engine. In 

 1784, he obtained letters patent for the parallel 

 motion, together with other contrivances ; and in 

 the year following he obtained a patent for an im- 

 proved smoke consuming furnace, the governor, 

 steam gauge, condenser gauge, and indicator. 



The next modification of the steam engine, of 

 any consequence, was that of Cartwright, who pro- 

 posed to condense the steam by means of cold wa- 

 ter applied to the external surface of the condenser. 

 The condenser consisted of two cylinders, one 

 placed within the other, the cold water flowing 

 through the inner and enveloping the outer. The 

 valves to change the steam were placed in the pis- 

 ton, so that the condenser was always open. This 

 engine was ingenious, but nothing more can be said 

 of it. The metallic piston, however, was invented 

 by Cartwright, and employed in his engine, and this 

 invention is of itself sufficient to rank him among 

 those to whom we are indebted for one of the 

 g?eat improvements in the steam engine. Much 

 was done by Mr Murray, of the firm Fenton, Mur- 

 ray, and Wood, of Leeds, in improving several parts 

 of the steam engine, which he included in his 

 patents of 1799, 1801, and 1802. About the same 

 period, Mr W. Murdoch, the well-known inventor 

 of gas lighting, made several important improve- 

 ments in constructing the cylinders and working 



