the theological mind since Tyndall's bombshell,* and I 

 have my foot pretty well into the difficulty. Our concern 

 is very sharply watehed. 



My Chemistry is still dragging through the press, the 

 Monthly has to be attended to, and I have just had one of 

 my eyes cauterized. From these complications you can 

 infer the difficulty I have in getting away. 



Old students of Mr. Spencer's works will recollect 

 the amusing vehemence with which he was attacked 

 in the British Quarterly Review of October, 1873, and 

 January, 1874, by a young Cambridge mathematician 

 named Moulton. The articles contained many lu- 

 dicrous misconceptions ; among other things the 

 writer actually accused Mr. Spencer of identifying 

 persistence of force with conservation of energy ! f 

 In two letters from Spencer to Youmans I find allu- 

 sions to this affair which have some interest, since 

 Cay ley and Sylvester are probably the two greatest 

 English mathematicians of the nineteenth century. 



April 77, 1874. 



Last night Hirst gave me the satisfactory information 

 that Cayley entirely agrees with me in the controversy with 

 Moulton, and thought Moulton deserved all he got. 



April 14, 1873. 



I received a few days ago a piece of information that 

 gratified me extremely. Sylvester came up to me at the 

 club and told me that he had recently been at Cam- 

 bridge, where he had dined at the fellows' table at the 

 college to which Moulton belongs. Moulton's name came 



* I. e., the celebrated Belfast Address. 



f The reply to the reviewer may be found in Spencer's Essays, vol. iii, 

 PP. 307-34L 

 15 



