18 
ADLER. 
Immediately after the success of these experiments and 
shortly before the article was written, Mr. Langley passed 
through a most depressing period of his official and personal 
life, and his feelings then were no doubt reflected in its 
closing words. In the month of September, 1896, his two 
principal associates in the Smithsonian Institution, George 
Brown Goode, a distinguished naturalist, who was in charge 
of the Museum, and William Crawford Winlock, already 
alluded to, had prematurely passed away, and their loss 
was a serious blow to Mr. Langley, whose friendships were 
deep ones. Of both these men he wrote memoirs — in fact, 
of Mr. Goode two, the longer of which, presented to the 
National Academy of Sciences, is at once a discriminating 
and affectionate tribute to a great man and a dear friend. 
For the next few years Mr. Langley’s time was not sc 
productive; his physical health was good, but the severe 
strain of his scientific labors and his personal losses tended to 
a depression of spirits which caused him to shrink from 
new work. In spite of his almost definitely announced in- 
tention no longer to carry on the work in flying-machines, 
he was led in 1898, through circumstances not clearly 
known, but which had to do to a certain extent with the 
Spanish-American war, to take up the building of a flying- 
machine large enough to carry a man, this work being 
undertaken under the Board of Ordnance and Fortification 
of the United States Army, and with an allotment made by 
that board for the purpose. He had meanwhile, after a little 
lapse of time, renewed his astropliysical work, which, 
through the improvement of the instruments he had in- 
vented, produced new and valuable results. The bolometer 
was brought to a greater degree of refinement than had ever 
been attained. The researches of the Astropliysical observa- 
tory had progressed to such a point as to justify the publica- 
tion of a remarkable volume of Annals; and an expedition 
made by him, to observe the solar eclipse of 1900, at Wades- 
boro, North Carolina, was signally successful. 
