Mechanical arithmetic, illustrated by the averaging machine. By W. S. AU-
CHINCLOSS. (Title)
ADDRESS OF VICE PRESIDENT JOHN TROWBRIDGE
On the Fritts selenium cells and batteries. By C. E. FRITTS
Relation between the electromotive force of a Daniell cell and the strength of
the zinc sulphate solution. By H. S. CARHART
'Upon a generator in use at Cornell University for producing oxygen and hy-
drogen gas by means of the dynamo machine. By WM. A. ANTHONY
Determination of the coëfficient of expansion of the speculum metal used for
Rowland's gratings. By WM. A. ROGERS