DE. EVEEETT ON THE EIGIDITY OE GLASS. 
153 
Savaet’s experiments on the torsion of brass wire lead to the result n— 3682. 
Kupffer’s values of M for nine different specimens of brass range from 8112 to 
11617, the value generally increasing with the specific gravity, and the two specimens 
which agree most nearly with our own in specific gravity show the following results : — 
Specific gravity 8-4465. Value of M 10783 
Specific gravity 8-4930. Value of M 11421. 
The values of M found by the same experimenter for steel range from 20569 to 21842. 
The values of a found by Kirchhoff, Wertheim, and Maxwell have already been 
given. They all differ widely from our own except in the case of steel. 
In conclusion we may state that, as our present form of apparatus is found extremely 
convenient, it is intended to use it for continuing the series of experiments which have 
been begun, with, however, an important modification, which will be made for the 
purpose of diminishing or removing the “ mechanical correction.” 
