AN ELECTRICAL THERMOSTAT 17 



The reason that the interruptions of the current follow each 

 other so rapidly is not quite clear to us. It may be due to a slight 

 jarring of the surface of the mercury at f. In any case the best 

 results are obtained with pure dry mercury, and when the platinum 

 wire touches the convex surface of the mercury column near its center. 



Hale Physical Laboratory, University of Colorado, U. S. A. 



