230 Notices respecting New Books. 



it is not a bit more obvious than by the usual methods of inves- 

 tigation, which do not require such elaborate experimental founda- 

 tions as this ingeniously complex method. In most of these appli- 

 cations of Carnot's principle, including such cases as the evolution 

 of the planetary systems, of which he gives an interesting account, 

 it does not seem quite clear whether friction is due to Carnot's 

 principle or Carnot's principle due to friction, or whether they are 

 the same. A general haziness as to this question lends a flavour 

 of crankiness to much of the book. Much of it is, however, very 

 interesting and most of it suggestive, as, for example, his consider- 

 ation of the objection that animals are too efficient. He begins by 

 the curious remark that they cannot be electromagnetic engines 

 because " it is obvious that there is no sensible absorption of electric 

 energy." Like others who border on crankdom, Mr. Parker is 

 very fond of that " it is obvious." It is obvious, on the other 

 hand, that there seems to be quite as much electric energy in bread 

 and butter as in zinc, and zinc certainly can drive electromagnetic 

 engines. But, as he points out, the real answer to any objection 

 to Carnot's principle founded on the efficiency of animals is that 

 animals are not examples of cyclic processes and that plants must 

 be included to complete the cycle; and then, he might have remarked, 

 the high temperature of the cycle is that at which the radiations 

 that can act on plants are evolved in sufficient intensity to act on 

 plants ; and this is a temperature comparable with that of the 

 sun. 



Mr. Parker's method of investigating Carnot's theorem is inter- 

 esting, partly because it is open to some objections. He starts 

 from the axiom that no work can be clone if heat be taken in and 

 given out all at a single temperature. The axiom is unfortunately 

 not true. If the working substance be reduced during part of its 

 cycle to absolute zero, no heat need ever be given out. Notwith- 

 standing this, there is considerable advantage in getting rid of " the 

 coldest body available ;" and if Mr. Parker had been content to 

 give the investigation in a concrete form that could be " under- 

 standed of the people," and not spread over several pages of gener- 

 alities, his method might have had a chance of being read. As it 

 is, most readers will be sickened by the first few pages. He tries 

 to cover every possible case by the generality of his statements, and 

 nevertheless makes all sorts of postulates that are passed over as 

 evident, so that his argument, being horribly scholastic, hides most 

 of the foundations on which it is based. He postulates in one 

 place that giving heat by friction is so absolutely identical with 

 giving heat by conduction, that the presence of a body is unnecessary 

 from which heat is at one time absorbed by conduction when at 

 another time heat is given to it by friction. Under such circum- 

 stances it is rather hard on this poor useful body to say that its 

 presence is unnecessary without any further explanation. 



The principal objection to Mr.' Parker's presentation of Thermo- 

 dynamic theory is that instead of calling attention continually to 



