JOCTOBEE 10, 1919] 



SCIENCE 



335 



\dse(J to throw light on the svihjeet under 

 investigation. His resource, courage and 

 devotion were extraordinary. 



In commencing his investigations on the 

 steam-engine he soon discovered that there 

 was a tremendous loss in the Newcomen 

 engine, which he thought might be reme- 

 died. This was the loss caused by conden- 

 sation of the steam on the cold metal walls 

 of the cylinder. He first commenced by 

 lining the walls with wood, a material of 

 low thermal conductivity. Though this im- 

 proved matters, he was not satisfied; his 

 intuition probably told him that there 

 should be some better solution of the prob- 

 lem, and doubtless he made many experi- 

 ments before he realized that the true solu- 

 tion lay in a condenser separate from the 

 cylinder of the engine. It is easy after 

 discovery to say, "How obvious and how 

 simple," but many of us here know how 

 difficult is any step of advance when 

 shrouded by unknown surroundings, and 

 we can well appreciate the courage and the 

 amount of investigation necessary before 

 James Watt thought himself justified in 

 trying the separate condenser. But to us 

 now, and to the youngest student who 

 knows the laws of steam as formulated by 

 Carnot, Joule and Kelvin, the separate eon- 

 denser is the obvious means of constructing 

 an economical condensing engine. 



"Watts experiments led him to a clear 

 view of the great importance of securing as 

 much expansion as possible in his engines. 

 The materials and appliances for boiler 

 and machine construction were at that 

 time so undeveloped that steam pressures 

 were practically limited to a few pounds 

 above atmospheric pressiire. The cylinders 

 and pistons of his engines were not con- 

 structed with the facility and accuracy to 

 which we are now accustomed, and chiefly 

 for these reasons expansion ratios of from 

 twofold to threefold were the usual prac- 



tise. Watt had given to the world an 

 engine which consumed from five to seven 

 pounds of coal per horse-power hour, or 

 one-quarter of the fuel previously used by 

 any engine. With tins consumption of 

 fuel its field under the conditions prevail- 

 ing at the time was practically unlimited. 

 What need was there, therefore, for com- 

 mercial reasons, to endeavor still further 

 to improve the engine at the risk of en- 

 countering fresh difficulties and greater 

 commercial embarrassments? The course 

 was rather for him and his partners to 

 devote all their energy to extend the 

 adoption of the engine as it stood, and this 

 they did, and to the Watt engine, con- 

 suming from five to seven pounds of coal 

 per horse-power, mankind owes the greatest 

 permanent advances in material welfare 

 recorded in history. 



With secondary modifications, it was the 

 prime mover in most general use for eighty 

 years, i. e. until the middle of last century. 

 It remained for others to carry the expan- 

 sion of steam still further in the compound, 

 triple, and, lastly, in the quadruple expan- 

 sion engine, which is the most economical 

 reciprocating engine of to-day. 



Watt had considered the practicability 

 of the turbine. He writes to his partner, 

 Boulton, in 1784: "The whole success of 

 the machine depends on the possibility of 

 prodigious velocities. In short, without 

 God makes it possible for things to move 

 them one thousand feet per second, it can 

 not do us much harm." The advance in 

 tools of precision, and a clearer knowledge 

 of the dynamics of rotating bodies, have 

 now made the speeds mentioned by Watt 

 feasible, and, indeed, common, everyday 

 practise. 



Turhines. The turbine of to-day carries 

 the expansion of steam much further than 

 has been found possible in any reciprocat- 

 ing engine, and owing to this property it 



