404 Dr. F. F. Blackman and Miss G. L. C. Matthaei. [Apr. 11, | 
The chamber is submerged in a fixed position on a wooden frame in a large 
rectangular glass cell full of water (a polished museum-jar measuring 
12 in. x 75 in. x 3°5 in.); see fig. 1. 
G 

This water-bath is closed above by an oblong thick cork cut to fit the 
mouth. Through appropriate holes in the cork pass:—the air-current 
