C. G. Rockwood—Motion of a Tower by Solar Heat. 177 
Art. XXV.—The Daily Motion of a Brick Tower, caused by Solar 
Heat ; by Prof. C. G. Rockwoop, Ph.D., Bowdoin College. 
THE observations which form the subject of the following 
re made in the spring of 1866. Some recent 
The walls were, however, made unusually heavy, and in order 
to have as firm a base as ible for the telescope, the upper 
Story was arched with brick, forming a solid and pretty firm bric 
floor, upon which now rests the stone pier of an equatorial. 
: t. e story below th tory, : 
beneath the brisk” arches, is occupied by the works of the 
tower clock, 
He dimensions of the tower are as follows: 
Side of the square at ground, ..-- ------------ 164 feet. 
we “  * top of brickwork, ------- 15 : 
Thickness of walls at first story,------------- 27 incl es. 
: «" & top of brickwork, .------ 6 f 
os “ where the arches spring,--- 20 — 
. Height to top of turret, _-. ~~. =---~----4---- ¥ eet. 
: “ a 
brickwork, ---- - 
“ floor of observatory room, -- -- ------ 75 
