54 PHILOSOPHICAL SOCIETY OF WASHINGTON. 
Grassmann’s, Hamilton’s, ete., consists in their ability to reveal new 
truths; a test which, according to Mr. Ziwet, Grassmann’s system 
successfully stands. 
Mr. M. H. DooxirtLe presented a communication on 
CAUSE AND CHANCE IN THE CONCURRENCE OF PHENOMENA. 
The author’s views set forth in this communication were stated 
to be preliminary and incomplete, and he therefore reserves them 
to be more fully elaborated before publication. 
20TH MEETING. May 18, 1885. 
The Chairman, Mr. G. W. H111, presided. 
Present, eleven members and three guests. 
Minutes of the nineteenth meeting, read, corrected, and adopted. 
Mr. G. L. RAVENE read a paper entitled 
THE ASTEROIDS. 
This communication elicited a general discussion, participated in 
by Messrs. KumMELL, Rirrer, BAKER, WoopwArD, ELLIorT, 
Pau., and HI. 
Mr. Rirrer then read a paper on 
SECULAR PERTURBATIONS OF POLYHYMNIA BY JUPITER, 
[Abstract. ] 
In the computations of these perturbations Gauss’s method has 
been employed, using the formule adapted to facilitate the appli- 
cation of this method given by Mr. G. W. Hill. 
The eccentricity of Polyhymnia being very large the circum- 
ference, with reference to the eccentric anomaly of Polyhymnia, 
has been divided into twenty-four parts. This is a greater number 
than necessary, but it seemed worth the additional labor required 
to have the forces and the other quantities involved for as large a 
number of points as practicable. 
