CORRESPONDENCE WITH DR. MANTELL. 215 



as I have long been accustomed to show in my class-room, 

 but not on so large a scale, nor with so high a power. 

 The thing that most surprises me is the right-angle re- 

 lation of the magnetism of iron and of most other things. 

 How far the attraction of other things than iron, by mag- 

 netism, may be resolved into electrical influences, it may 

 not perhaps be easy to decide. We know that currents of 

 electricity accompany the magnetic influences, and perhaps 

 cause them ; but, after all, what is electricity ? We are 

 perhaps as far as ever from answering this question ; but 

 we appear to be on the eve of great things, just opening 

 a vista whose termination no one can see. 



TO DR. MANTELL. 



NEW HAVEX, May 27, 1846. 



I AM now, in a day or two, to begin my summer 



course, which will end about August 8. J. D. D. having 

 finished the zoophytes, is now engaged on his geology of 

 the regions visited by the squadron ; and B. S., Jr., is deep 

 in an elementary work on chemistry for academies and 

 schools. I regret that the work is printing while it is still 

 writing, not always a safe course even for a veteran 

 author, and always anxious for a young one ; but we are all 

 on the qui vive, and hope to escape any very important 

 mistakes. You will see that we have a war with Mexico. 

 It might have been avoided ; and all wars that can be 

 avoided are of course wrong. As regards Mexico, there 

 is perhaps little to fear ; but we greatly dread being drawn 

 into a war with you or with France, for the balance of 

 power, or any other phantasm of politicians. You will 

 have observed that a small American army has sus- 

 tained itself against, and beaten, four times their number ; 

 and there is reason to fear that the military spirit, now fast 

 rising in this nation, and popular with our democracy, will 

 kindle into ambition of conquest, which, I suppose, you and 

 your neighbor will not permit to go, without being checked, 



