MAXWELL'S TYNDALLIC ODE 175 



The following instance of domestic evolution was submitted to Mr Herbert 

 Spencer who was present in Section A. 



"The ancients made enemies saved from the slaughter 



Into hewers of wood and drawers of water ; 

 We moderns, reversing arrangements so rude, 

 Prefer ewers of water and drawers of wood." 



Mr Spencer in the course of his remarks regretted that so many members of 

 the Section were in the habit of employing the word Force in a sense too limited 

 and definite to be of any use in a complete theory of evolution. He had himself 

 always been careful to preserve that largeness of meaning which was too often lost 

 sight of in elementary works. This was best done by using the word sometimes 

 in one sense and sometimes in another and in this way he trusted that he had 

 made the word occupy a sufficiently large field of thought. The operations of 

 differentiation and integration which appeared, from the language of previous 

 speakers, to be already in some degree familiar to members of the Section, were, he 

 observed, essential steps in the normal progress of evolution. It gave him great 

 pleasure to learn that members of Section A were now turning their attention to 

 these processes. He was also glad to see how entirely the Section concurred with 

 his view of nervous action as a wave of accumulation, and he hoped they would 

 also direct their attention to the mode in which the exhausted nerve recuperates its 

 energy by absorption of heat from the neighbouring tissues which form its environ- 

 ment. In Professor Tait's new edition of his work on Thermodynamics he had no 

 doubt this subject would be ably treated. 



Mr Spencer, whose speech was throughout one of the most didactive, exhaustive 

 and automatic efforts ever exerted, then left the Section. 



In Section B, Prof. W. K. Clifford read a paper on Chemical equations 1 . The 

 equation 



was the first selected. He observed that both the constituents of the left member 

 were in the liquid state and that though the resultant might not be familiar to some 

 members, he could warrant it 2XL. From an equation of similar form 



H a + a, = 2HCI 

 he deduced by an easy transformation 



whence by extracting the square root 



H-Cl=o or H=Cl, 



a result even more remarkable than that obtained by Sir B. C. Brodie. 



dp 

 -Jf 



1 Clifford's paper On the General Equations of Chemical Decomposition was read before 

 Section A; but the Title only is given in the B. A. Reports (1874). An abstract appeared in 

 Nature, Sept. 24, 1874, and was reprinted in the Preface to the Mathematical Papers, p. xxv. 

 Maxwell's amusing parody has a striking superficial resemblance to the original. 



