i86 



E. A. STEPHENSON 



sides of the base plate A. D is a brass rod brazed to the block B, 

 making D-B-S a continuous piece pivoted at V, Fig. 6. S', Fig. 6, 

 is a steel spring pressing firmly against the under side of D so that 



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[■* Therm o s t at *** m \ 



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j.r r r r f r 



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Fig. 2. — Front elevation of the oven 



Ca 



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H 



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it is held close to the tip of screw C even when the contacts Pt are 

 broken. M and M' are mica strips insulating R and R' from the 



rest of the device. W is a 

 copper washer. H, Fig. 6, 

 represents holes in the base 

 plate A, through which bolts 

 pass that hold the regulator 

 against the back of the oven. 

 A small condenser, not shown, 

 is shunted around K and Pt, 

 Fig. 6. 



Since the temperature co- 

 efficient of copper is greater 

 than that of steel, a rise in 

 temperature causes the strip 5 

 to bend the contacts Pt away 

 from the tips of the screws K and K' , and thus cut out the coils 

 Nos. 3 and 5. The fall of temperature which results causes a 

 reversal of the bend of the strip until the contacts are again made 



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Fig. 3. — End elevation of the oven 



