SAMUEL I'llvRPOXT LANGLEY. 



THE SCIENTIFIC WORK OF SAMUEL PIERPOXT 

 EANGLEY. 



BY PROF. E. C. PICKERING. 



The Chief Justice: I am gratified, ladies and gentlemen, to 

 present a gentleman, with whose reputation yon are all well ac- 

 quainted and who was associated years ago in eclipse expeditions 

 with Mr. Langley — Professor Pickering, Director of the Harvard 

 Observatory. 



Professor Pickering: Mr. Chief Justice, ladies and gentlemen: 

 In comparing the paper we have just heard with that I am about to 

 read to you, you will probably be impressed, as I have been, with 

 the manner in which two minds, in dealing with the same facts fr6m 

 wholly different standpoints, have arrived so closely at the same re- 

 sults. Possibly this coincidence may justify us in the belief that these 

 facts are really the most important in Langley's career. The fact that 

 they should have impressed one whose mind has been occupied by 

 such different lines of work from those of Langley I think also 

 justifies me in the very high degree of value I attach to them 

 in the paper which I am presenting to you. Possibly when you have 

 heard my paper you may suspect that in some respects Doctor White 

 and I have interchanged the subjects which were assigned to us. 



The scientific work of Samuel Pierpont Langley extended over a 

 period of forty years, and occupied his entire strength and energy 

 during a large part of this time. It is evidently impossible to do 

 justice to such a subject in the time allotted to me this evening. 

 Fortunately, he lived to publish his most important work and thus 

 make it known to the world. Admirable reviews of it have also 

 recently appeared in the technical journals, recalling it to the pro- 

 fessional physicist and astronomer. It remains for me to tell you 

 how it appears to one who knew him well during nearly this entire 

 period, who prized long discussions with him regarding his work 

 during his earlier years, and whose affection and friendship for him 

 never waned and were interrupted only by his death. 



His work in science naturally divides itself into two parts, one 

 while Director of the Allegheny Observatory, and the other while 

 Secretary of the Smithsonian Institution. Each of these extended 

 over a period of about twenty years, and was conducted in surround- 

 ings differing in almost every respect. His remarkable skill as a 



