THE 



AMERICAN JOURNAL OF SCIENCE 



[THIRD SERIES.] 



Aet. I. — The History of a Doctrine • Address by S. P. 

 Langley, retiring President of the American Association 

 for the Advancement of Science.* 



" Man, being the servant and interpreter of nature, can do and understand so 

 much, and so much only, as he has observed, in fact or in thought, of the course of 

 nature. Beyond this he neither knows anything nor can do anything."— Bacon's 

 Novum Organum, aphorism 1. 



In these days, when a man can take bnt a very little portion 

 of knowledge to be his province, it has become customary that 

 your president's address shall deal with some limited topic, 

 with which his own labors have made him familiar; and 

 accordingly I have selected as my theme, the history of our 

 present views about radiant energy, not only because of the 

 intrinsic importance of the subject, but because the study of 

 this energy in the form of radiant heat is one to which I 

 have given special attention. 



Just as the observing youth, who leaves his own household 

 to look abroad for himself, comes back with the report that 

 the world, after all, is very like his own family, so may the 

 specialist, when he looks out from his own department, be sur- 

 prised to find that, after all, the history of the narrowest 

 specialty is strangely like that of scientific doctrine in general, 

 and contains the same lessons for us. To find some of the 

 most useful ones, it is important, however, to look with our 

 own eyes at the very words of the masters themselves, and to 



* This Address appears here complete with the notes that have not hitherto 

 been published. — -Eds. 

 Am. Jour. Scl— Third Series, Vol. XXXVII, No. 217.— Jan., 1889. 

 1 



