650 



SCIENCE. 



[N. S. Vol. XVIII. No. 464. 



from temperature T^ to temperature T„ 

 constituting a steady sweep. This process 

 being steady, the degeneration occurring 

 in a given interval of time must be pro- 

 portional to the time. The quantity of 

 heat transferred is also proportional to the 

 time. Therefore, the amount of degenera- 

 tion is proportional to the quantity of heat 

 transferred. The dependence of this kind 

 of degeneration upon temperature will be 

 considered later. 



Corollary.— The thermodynamic regener- 

 ation which is represented by the transfer 

 of heat from a low temperature T, to a 

 high temperature T^ by a reversible process 

 is proportional to the heat transferred. 



8. THE SECOND LAW OF THEEMODYNAMICS. 



(a) The degeneration of a system which 

 accompanies a sweeping process can not be 

 directly repaired, nor can it be repaired 

 by any means without the creation of a 

 compensating degeneration in some other 

 system. 



This is an entirely general statement of 

 the second law. The direct repair of the 

 degeneration due to a sweeping process 

 means the undoing of the havoc wrought 

 by the sweep by allowing the sweep to 

 perform itself backwards! This notion of 

 direct repair is introduced into this gen- 

 eral statement of the second law in order 

 that each of the following particular state- 

 ments of the law, namely, (&), (c) and 

 {d) may correspond exactly in form to the 

 general statement {a). A slightly modi- 

 fied general statement of the second law is 

 the following: 



(a) Thermodynamic degeneration and 

 regeneration are always balanced in a re- 

 versible process, while degeneration always 

 exceeds regeneration in any process which 

 is in any way sweeping in character. 



(b) Heat can not pass directly from a 

 cold body to a hot body, nor can heat be 

 transferred from a cold body to a hot body 

 by any means without compensation. 



(c) Heat can not be converted directly 

 into work, nor can heat be converted into 

 work by any means without compensation. 



The direct conversion of heat into work 

 (see discussion following (a) above) would 

 be simply the reverse of any of the ordi- 

 nary sweeping processes which involve the 

 degeneration of work into heat. Thus, 

 work is degenerated into heat in the bear- 

 ing of a rotating shaft, and we all know 

 that to reverse the motion of the shaft 

 will not cause the bearing to grow cold 

 and the heat so lost to appear as work 

 helping to turn the shaft! 



{d) A gas can not pass directly from a 

 region of low pressure to a region of high 

 pressure, nor can a gas be transferred from 

 a region of low pressure to a region of 

 high pressure by any means without com- 

 pensation. 



The compensation involved in the trans- 

 fer of a gas from a region of low pressure 

 to a region of high pressure by means of 

 a pump is the degeneration into heat of 

 the work spent in driving the pump. 



The repeated statement of self-evident 

 facts in these statements of the second law 

 of thermodynamics may seem ridiculous to 

 the intelligent reader, but it must be re- 

 membered that but few persons realize 

 that the second law of thermodjoiamics is a 

 statement of a fact which every one knows, 

 together with a generalizing clause which 

 when once thoroughly understood is almost 

 if not quite self-evident. I can not refrain 

 from one more statement of the second 

 law, the oldest English version of it : 



Humpty Diimpty sat on a wall. 



Humpty Dumpty had a great fall. 



All the King's horses and all the King's men 



Can not put Humpty Dumpty together again. 



This is perhaps the most dignified of all 

 the statements of the second law of thermo- 

 dj^namics, inasmuch as it omits all non- 

 sense about direct repair and refers at once 

 to external means. 



