PREFATORY NOTE 



The present number commemorates the one-hundredth anni- 

 versary of the founding of the American Journal of Science by 

 Benjamin Silliman in July, 1818. The opening chapter gives 

 a somewhat detailed account of the early days of the Journal, 

 with a sketch of its subsequent history. The remaining chap- 

 ters, eleven in number, are devoted to the principal branches of 

 science which have been prominent in the pages of the Journal. 

 They have been written with a view to showing in each case 

 the position of the science in 1818 and the general progress made 

 during the century; special prominence is given to American 

 science and particularly to the contributions to it to be found 

 in the Journal's pages. References to specific papers in the 

 Journal are in most cases included in. the text and give simply 

 volume, page, and date, as (24, 105, 1833) ; when these and 

 other references are in considerable number they have been 

 brought together as a Bibliography at the end of the chapter. 



The entire cost of the present number is defrayed from the 

 income of the Mrs. Hepsa Ely Silliman Memorial Fund, estab- 

 lished under the will of Augustus Ely Silliman, a nephew of 

 Benjamin Silliman, who died in 1884. Certain of the chapters 

 here printed have been made the basis of a series of seven Silli- 

 man Lectures in accordance with the terms of that gift. The 

 selection of these lectures has been determined by the conveni- 

 ence of the gentlemen concerned and in part also by the nature 

 of the subject. A special volume reproducing this number, with 

 some important additions, will soon be published by the Yale 

 University Press. 



