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PHILOSOPHICAL SOCIETY OF WASHINGTON. 
27th Meeting. ' MAlien 30, 1887, 
The Chairman presided. 
Present, twelve members and two guests. 
Mr. R. S. Woodward read a paper on 
THE FREE COOLING OF A HOMOGENEOUS SPHERE INITIALLY 
HEATED TO A UNIFORM TEMPERATURE. 
[This paper appeared in full in the Annals of Mathematics. 4°. Char¬ 
lottesville, Va. 1887, June; vol. 3, no. 3, pp. 75-88. Also separately 
printed.] 
Remarks were made on this paper by Messrs. Kummell, HiLLy 
and the Chairman. 
Mr. Kummell read a paper on 
THE BRACHISTHODE ON THE HELICOID. 
[Abstract.] 
The characteristics of this class of curves and the methods of com¬ 
puting their lengths in the several cases were explained and dis¬ 
cussed. Accurately constructed stereoscopic diagrams of several of 
these curves were exhibited. 
[This paper is expected to appear in the Mathematical Visitor.] 
28th Meeting. April 13, 1887 
The Chairman presided. 
Present, nineteen members and one guest. 
Mr. G. W. Hill read a paper on 
THE MOTION OF HYPERION. 
Although designed to meet the special case presented by Hyperion, 
Mr. Hill’s paper treated the general problem of three bodies under 
the restrictions that they are all nearly in the same plane and that 
