72 TRANSACTIONS OF THE [yan. 21, 
distinguished members of the Academy; and to that of Mr. 
Robert H. Lamborn, well known as an archeologist. Prof. 
Martin made a brief memorial address. 
In view of the fact that it was most appropriate for the Section 
of Biology to take suitable action regarding a memorial of Mr. 
Lawrence, it was moved and carried that the President of the 
Academy appoint a committee of one to prepare a memorial of 
Mr. Lamborn. Prof. D. S. Martin was subsequently appointed. 
The paper of the evening was then read by Prof. R. 8S. Wood- 
ward, entitled ‘“‘The Condition of the Interior of the Earth,” 
of which the following is an abstract : 
The two envelopes of the earth, the atmosphere and the ocean 
are important factors in the problem of the interior, and yet we 
know less of the condition of the outer atmosphere than of the 
inner earth. The atmosphere’s shape we can calculate with 
some approximation to the truth as an oblate spheroid, whose 
polar radius is 5.4 times the earth’s radius, and whose equatorial 
radius is 7.6 times the latter. This shape is determined by cen- 
trifugal force and gravity. Its bulk is 310 times that of the 
earth, but its mass is only one-millionth that of the latter. If 
we speak of the latter as 6642 x 10'*® tons we can get some con- 
ception of the mass of the atmosphere, and of its extreme tenuity 
in the outer portions. 
Our inferences regarding the interior of the earth rest chiefly 
upon four facts, viz. 
1. Its shape and size, which are known with great accuracy. 
2. Its surface density, 2.6. 
3. Its mean density, 5.58, which is probably accurate within 
two units in the second decimal place. 
4, The precession ratio o in which C is the moment of in- 
ertia of the earth with respect to the polar axis, and A is the 
moment of inertia with respect to an equatorial axis. 
These facts limit the distribution of the earth’s mass. The 
density of the mass must increase from the surface toward the_ 
center. Various laws of its increase have been proposed, of 
which that of Laplace seems to be on the whole the most plausible. 
