184 IOWA ACADEMY OP SCIENCE 
ities, and thus indicate when the best conditions exist. Such a thermopile 
may be easily made in any laboratory shop from iron and copper wires mounted 
on an ebonite or wooden frame, and can he located so as to he used during 
weighing without being in the way. 
Cor'iTes/Doncling Ternfaer'^Ture Dijji 
