IV ADVERTISEMENT. 



hered to, and when French or English papers have 

 been reported on, the originals have been consulted. 

 For those errors which may have escaped him, the 

 Translator requests the indulgence of his Reader^ and 

 has only to hope that his undertaking may assist his 

 countrymen in exploring a field of science rich in in- 

 terest, and which amply repays the time and labour 

 spent in its cultivation. 



W. F. 



Oct. 1, 1839. 



