Manchester Memoirs, Vol. lix. (191 5), No. 11. 15 



The pressure of the steam employed was hardly greater 

 than the pressure of the atmosphere. 



About 171 1 Newcomen's machine began to be used in 

 coal mines for pumping water. It came into general use 

 about 1725, and remained in use about three quarters of 

 a century. 



After Newcomen, fresh improvements of the highest 

 importance were introduced by James Watt. The work 

 of this celebrated inventor deserves a slightly larger con- 

 sideration. 



James Watt was born at Greenock on January 19th, 

 1736. He learned the trade of a scientific instrument 

 maker in London. In 1756 he tried to continue his trade 

 at Glasgow, but the guilds of the city prevented him, not 

 wishing to recognise a workman who had not served 

 an apprenticeship of the required length of time. The 

 Glasgow college took him under its protection and in 

 1757 he was established with the title of constructor of 

 mathematical instruments to the University. One day he 

 was required to repair a working model of Newcomen's 

 machine which belonged to the University. This led him 

 to study the steam engine, and was the starting point of 

 a long series of improvements. 



Watt was struck by the enormous wastage of heat 

 inherent in the method of condensation invented by Savery 

 and adopted by Newcomen. To obviate this he placed 

 beside the cylinder a second vessel, into which the steam 

 from the cylinder could escape, there to be condensed 

 by the internal or external use of cold water. By 

 this invention of the so-called condensor (in 1763), the 

 alternate heating and cooling of the cylinder was avoided, 

 and it became possible to keep the cylinder warm by 

 covering it with a jacket of some bad conductor of 

 heat. 



