308 PROCEEDINGS OF THE AMERICAN ACADEMY. 



a lead tube bent into solenoidal form. The bar was placed horizontal 

 within the solenoid, the axis of which was vertical. 



The electrical resistance in absolute c. g. s. measure was about 112,200 

 at 17°. 4. 



From the observation of September 20, 1898, the temperature-coefRcient 

 of conductivity between 20°.9 and 61°.2 appeared to be —0.00120. The 

 observations of September 27, between 17°.4 and 67°. 4, gave —0.00116. 

 We may take the mean, —0.00118. In both cases the coefficient was 

 calculated by the formula 



C e-ffi ' Cond. at high temp. — cond. at low temp, 



Cond. at low temp. X (high temp. — low temp.) 



without reference to 0°. 



E. H. H. 



