Preface. ix 



Besides the acknowledgments that will be found in 

 the following pages, made to friends for whose aid 

 and suggestions I am under obligations to them, I 

 must make here a special mention of the kind and 

 helpful assistance, sympathy, and information which 

 I have received from Mr. George Rumford Baldwin of 

 Woburn, Massachusetts ; Mr. Joseph B. Walker, 

 of Concord, New Hampshire; Dr. H. Bence Jones, 

 of London, Secretary of the Royal Institution of 

 Great Britain ; Mons. Jules Marcou, of Paris ; and 

 Mr. G. Henry Horstmann, United States Consul at 

 Munich. 



A search which I was privileged to make among 

 the effects of Sarah, Countess of Rumford, in Concord, 

 New Hampshire, was rewarded, as will be seen, by the 

 discovery of much curious and interesting matter. 



I hardly need to add, that, though I have done this 

 work as a labor of love in the service, as well as at 

 the request, of the American Academy of Arts and 

 Sciences, I alone am responsible for any errors which 

 it may containj and for the statements and opinions 

 expressed in it. 



G. E. E. 



