

To JOHN GEORGE CHILDREN, ES^UIUE, 



F. R. S. L. & E. 



THE kindness which a traveller receives when in a 

 distant land, must ever be among his most pleasing 

 recollections your attentions therefore to me, during 

 any short residence in London a few years since, can- 

 not easily be forgotten. Suffer me, then, to inscribe 

 this little work to you as a token of my gratitude. 



Our pursuits in the Natural and Physical Sciences 

 have been congenial. Your interesting researches 

 with your original and magnificent Galvanic Battery, 

 first drew my attention to the calorific effects of that 

 mysterious agent; and your works on Natural His- 

 tory have stimulated my exertions in the same fasci- 

 nating pursuit. 



A large portion of your time and fortune have been 

 devoted to the patronage or the cultivation of Natu- 

 ral Science so that the dedication of this work to 

 you, if it w-ere infinitely more worthy of your accept- 

 ance, would be due from me, both as a tribute of 

 liigh respect, as well as of grateful acknowledgment. 



Philadelphia, October 1st, 1832, 



ivi36194:l 



