30 
PHILOSOPHICAL SOCIETY OP WASHINGTON. 
Table I. 
Membership and Attendance of the Philosophical Society, by Years. 
Y ear. 
'P 
S 
o; 
a;> 
Net active mem¬ 
bership and date 
of same. 
Average attend¬ 
ance at ordinary 
meetings. 
Katio of attend¬ 
ance to mem¬ 
bership. 
New societies or 
ganized. 
1871.— 
17 
44, Mar. 13 .. 
* 
1872 ... 
14 
1873. 
23 
1874..._. 
33 
114, June. 
1875._- 
22 
124, Dec. — 
35 
.29 
1876-_- 
8 
37 
1877 — 
10 
40 
1878 — 
9 
40 
1879 
22 
135, Apr. 2 __ 
40 
.29 
Anth. Soc., Feb. 17. 
1880 
19 
154, July 20__ 
41 
.27 
Biol. Soc., Dec. 3. 
1881 .... 
13 
152, July 18 — 
38' 
.25 
1882 
16 
149, May_ 
34 
.23 
1883. 
17 
149, Dec. 31. 
38 
.26 
Math. Sec., Mar. 29. 
1884. 
35 
173, Dec. 20__ 
42 
.26 
Chem. Soc., Jan. 31. 
1885-_- 
22 
179, Jan. 16__ 
47 
.27 
1886.— 
18 
183, Dec. 18_- 
47 
.26 
1887.— 
15 
191, Dec. l._. 
49 
.26 
Mean_ 
18 
40 
.265 
In a general way there has been a continuous growth of the So¬ 
ciety as regards membership, and the rate of growth, whether con¬ 
sidered as a geometric ratio or as an arithmetic increment, has 
progressively diminished. The average attendance has likewise 
increased, but its law is not evident. The ratio of attendance to 
membership has ranged in ten recorded years from .23 to .29, the 
mean being .265. 
The total active membership passed through a secondary maximum 
in 1880 and a minimum in 1882-’83. The current attendance 
exhibits a subsidiary maximum from 1877-’80 and a minimum in 
1882. The curve of accessions shows maxima in 1874, 1879, and 
1884. While there are many series of contemporaneous events 
with which these might be compared, one only will be considered, 
namely, the formation of other scientific societies in Washington 
and the formation of the Mathematical Section within our Society. 
