114 LECTURES TO SCIENCE TEACHERS. 



the mechanical skill and appliances of those days were 

 unable to cope with the demands made upon them, and 

 that pipes, joints, and cocks, leaked and gave way. 



It was at this time, while the new steam power was struggling 

 into existence, that Newcomen (the father of the modern 

 steam-engine, as I believe him to be) came forward with that 

 invention which in its leading features is used by us to this 

 day. Newcomen said : I will show you a mode of making 

 steam raise water where the pressure of steam per square inch 

 need not bear any relation to the height to which the water 

 has to be lifted ; I will show you that the relation between 

 the resistance and the power necessary to overcome that 

 resistance may be adjusted by causing the steam to act upon 

 some surface not that of the water, and that this surface 

 may be a solid moving freely (but practically steam tight) 

 in a cylinder (this surface being the true piston at last), and 

 that by suitable means I can cause this surface acted upon by 

 the steam to work the other surface whicg is to act upon the 

 water, and that by the due adjustment of the relation be- 

 tween these two surfaces I may make steam of low pressure 

 (or as in practice I intend to effect it, a portion of the 

 pressure of the atmosphere) master of a resistance of hundreds 

 of feet of head of water, and that thus steam barely powerful 

 enough to overcome the atmospheric resistance shall master 

 the resistance involved in the raising of water from out 

 of the deepest mine, or shall produce the high pressure 

 required to distribute water throughout the contracted and 

 tortuous wooden mains for a town supply. 



An engine of this description (a Newcomen engine) was 

 put up in York Buildings to come to the rescue of, and 

 to supersede, the Savery engine which I have previously 

 described. 



Belidor (that most conscientious of writers) states in his 

 Architecture Hydraulique, that he heard of this engine suc- 

 ceeding Savery's at York Buildings, and that he then visited 

 one which was put up at Fresnes ; this he did several times 

 to enable him, as he says, to do justice to it, and to give his 

 readers full information upon it. He has given the fullest 

 possible information, and has left us drawings so complete 

 that any workman in an engineer's factory could at the pre- 

 sent day reproduce from those drawings the very engine that 

 Belidor wrote of in 1737. The leading dimensions were as 



