*2 SCIENCE REMAKING THE WORLD 



the prison walls of the containing vessel as a motive 

 power for his own purposes. This was accomplished 

 by the simple expedient of making one of the partitions 

 movable. If a crowd of molecules are imprisoned in a 

 steel cylinder they bump incessantly against all the sides 

 equally as though trying to get out. If, now, one of 

 the ends is a piston head, slipping easily in the cylinder, 

 this gets shoved out by the constant pounding until 

 finally the exhausted molecules make their escape into 

 the open air. 



WHAT HAPPENS IN AN ENGINE? If the molecules 

 are crowded into a prison half the size by shoving in the 

 piston partition they naturally knock against it twice 

 as often. This observation is so obvious that you will 

 probably not appreciate it properly until you know that 

 it is called "Boyle's Law." Then again if you shove 

 in the piston head suddenly and crowd the molecules 

 into smaller space they naturally get hot about it and 

 do more knocking than ever. The hotter they get the 

 harder they pound against the prison walls. This also 

 is so easy to see that you will not get credit for it, even 

 from yourself, unless you dignify it by calling it the 

 "Law of Charles" and expressit in such words as: "The 

 pressure of a gas at constant volume is proportional to 

 the absolute temperature." 



Having now in mind the two laws that all anarchic 

 molecules obey we can see how we can get the most work 

 out of a given number of them. Obviously this will be, 

 first, to confine them in the smallest space and force 

 them to fight their way out to the largest possible space. 

 Secondly, to get them as hot as possible and let them 



