AN ELECTRIC THERMOREGULATOR. 



863 



makes the primary circuit. When the secondary circuit is auto- 

 matically broken a spring forces the wedg-e back to its former 

 position, breaking the primary circuit. This device is shown 

 diagram atically in Figure 53. 



The thermoregiilator is constructed of glass and consists 

 of an elongated bulb to be immersed in the water <»f the oven 

 jacket, to which a IT-shaped tube of 6 mm. bore is attached by 

 a short horizontal tube of the same diameter. The upper end 

 of the bulb is provided with a stop-cock by means of which it 

 may be opened or closed. The U-shaped tube is sealed at the 



neaalati 



Figure 53. 

 moregulator. 



Diagram showing arrangement of a new electric ther- 



end nearest to the bulb and open at the other. The poles are 

 arranged as follows: A platinum-tipped copper wire is sealed 

 into a small tube, which in turn is pushed into the arm of the 

 U-tube and sealed in place, thus closing the latter. The plati- 

 num point is placed about halfway between the middle of the 

 U-tube and its base. The other pole is moveable in the open 

 arm of the U-tube. It may be so adjusted that when the main 

 circuit is broken the secondary will also be broken, automati- 

 cally and at any desired temperature. The main points in the 



