APRIL 4, 1921 proceedings: philosophical society 169 



Great range together with constancy may be realized by the use of an 

 auxiliary compensator which consists of a motor geared to the contact of the 

 rheostat which controls the fixed heat supply to the bath. The direction of 

 rotation of this motor is periodically reversed by a relay in such a manner 

 that the fixed heating tends to be slowly increased or decreased during the 

 parts of the cycle of operation of the regulator during which an increased or 

 decreased supply of energy is required by the bath. Thus the fixed heating 

 is increased or decreased as the bath requires an increased or decreased sup- 

 ply of energv^ over one or more complete cycles of operation of the regulator. 



It is seen that this method of regulation requires only a temporary departure 

 of the bath temperature from its normal value in order that a permanent 

 change in the heating be efTected, whereas without the auxiliary' compensating 

 mechanism the change in the heating persists only during the time that the 

 bath temperature remains above or below normal. 



The auxiliary compensator may be used in connection with the oscillating 

 contact regulator to secure steadiness, constancy, and range to a high degree. 



Discussion: This paper was discussed by Messrs. White, Beall, Breit, 

 TucKERMAN, Ferner, Wenner, Adams, Van Dusen, Heyl, Mueller, and 



SOSMAN. 



S. J. Mauchly, Recording Secretary 



