336 



BABCOCK. 



d. Thermometer Switch. 



Double throw, four blade, all copper knife switch especially 

 constructed. Used to connect either of the two thermom- 

 eters to the l^ridge. Later work showed that mercury 

 cup links are more satisfactory for this purpose. 



e. Galvanometer. 



High sensitivity, Leeds and Northrup, D'Arsonval instru- 

 ment,^^ type b: resistance 12 ohms; period 5 sees., sensi- 



CALIBRATION TUBE 



OIL LEVEL 



COVER or DRA55 

 ENCLOSING VE55EL 



CALORIMETER COVER- 



CALORIMETER TUBE- 



OBSERVING 

 THERMOMETER 



STANDARD 



THERMOMETER 



SiEEEL CALIBRATION 

 TUBE 



CMS 



Figure 6. 



tivity 5 mm. per micro-volt at a scale distance of 1 meter. 

 Supported on brick wall. Scale observed by telescope at 

 distance of 2.4 meters. Scale divisions were arbitrary but 

 so spaced that a movement of the bridge wire equivalent 

 to 0.00001 ohm produced a deflection of approximately 

 1*0 of a scale division. A change in resistance of 0.00001 

 ohm was equivalent to about 0.0001° C. on the standard 

 thermometer. 



11 Leeds and Northrup Bulletin, no. 228. 



