CAPTIVE MOLECULES 



his own mind. Much less is it possible for him to say 

 precisely what share of his progress has been due to 

 chance suggestions of others. But it is interesting, at 

 least, to recall this association of Watt with the greatest 

 experimenter of his age in a closely allied field. Ques- 

 tions of suggestion aside, it illustrates the technical 

 quality of Watt's mind, making it obvious that he was 

 no mere ingenious mechanic, who stumbled upon his 

 invention. He was, in point of fact, a carefully trained 

 scientific experimenter, fully equipped with all the 

 special knowledge of his time in its application to the 

 particular branch of pneumatics to which he gave 

 attention. 



The first and most obvious defect in the Newcomen 

 engine was, as Watt discovered, that the alternating 

 cooling and heating of the cylinder resulted in an un- 

 avoidable waste of energy. The apparatus worked, it 

 will be recalled, by the introduction of steam into a 

 vertical cylinder beneath the piston, the cylinder being 

 open above the piston to admit the air. The piston 

 rod connected with a beam suspended in the middle, 

 which operated the pump, and which was weighted at 

 one end in order to facilitate the raising of the piston. 

 The steam, introduced under low pressure, scarcely 

 more than counteracted the pressure of the air, the 

 raising of the piston being largely accomplished by the 

 weight in question. 



Of course the introduction of the steam heated the 

 cylinder. In order to condense the steam and produce 

 a vacuum, water was injected, the cylinder being there- 

 by cooled. A vacuum being thus produced beneath 



[95] 



