watt's labours in the steam-engine. 389 



men's engines of known dimensions ; the quantity of 

 cold water that must be injected into the cylinder to 

 give a certain force to the piston's descending oscillation ; 

 and finally the elasticity of steam at various tempera- 

 tures. 



Hei'e was enough to occupy the life of a laborious 

 physicist, yet Watt found means to conduct all these 

 numerous and difficult researches to a good termination, 

 without the work of the shop suffering thereby. Dr. 

 Cleland wished, not long since, to take me to the house, 

 near the port of Glasgow, whither our associate retired 

 on quitting his tools, to become an experimenter. It was 

 razed to the ground ! Our anger was keen but of short 

 duration. Within the area, still visible of the founda- 

 tions, ten or twelve vigorous workmen appeared to be 

 occupied in sanctifying the cradle of modern steam- 

 engines ; they were hammering with redoubled blows 

 various portions of boilers, the united dimensions of 

 which certainly equalled those of the humble dwelling 

 that had disappeared there. On such a spot, and under 

 such circumstances, the most elegant mansion, the most 

 sumptuous monument, the finest statue, would have 

 awakened less reflection than those colossal boilers. 



If the properties of steam are still present to your 

 mind, you will perceive at a glance, that the economic 

 working of Newcomen's engine seems to require two 

 irreconcilable conditions. When the piston descends, 

 the cylinder is required to be cold, otherwise it meets 

 some steam there, still very elastic, which retards the 

 operation very much, and diminishes the effect of the 

 external atmosphere. Then, when steam at the temper- 

 ature of 100° flows into that same cylinder and finds it 

 cold, the steam restores its heat by becoming partially 



