MECHANISM OF NATURE 



through the small stoppered tube E. Let the gas 

 or vapor be at any convenient temperature, while 

 the piston is down within 30 1-3 inch of the bottom 

 of the; Cylinder. Let a constant pressure be exerted 



on the piston through the means of the 100 Ibs. 

 weight. Then if by means of the basin of burn- 

 ing charcoal, or by some better means, the tem- 

 perature of the gas is raised one degree, the piston 

 with its constant pressure of 100 Ibs. is driven out 

 1-9 of an inch. And this expansion (that is, 1-273 

 in volume) will be constant under constant pres- 

 sure, for every gas under any degree of heat while 

 the gas or vapor remains such. And reversing the 

 experiment that is, by increased pressure to re- 

 duce the volume of gas (putting the piston down 

 1-9 of an inch) 1-273 in volume will raise any 

 gas or vapor through one degree of heat. But the 

 increase of pressure required, while uniform for 

 154 



