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A TEXTBOOK OF PHYSIOLOGY 



The unit by which work is measured is the kilogramme-metre 

 (kgm.). This is the force necessary to raise a kilogramme vertically 

 through 1 metre from the earth's surface.* 



FIG. 183. BOMB CALORIMETER. (Berthelot.) 



.-', Water jacket; B, water calorimeter; C, bomb; D, stirrer worked by motor G\ 

 E, thermometer ; F, cable carrying wires to o and d. 



The unit by which heat is measured is the Calorie. This is the 

 heat required to raise 1 kilogramme of water through 1 C. (preferably 

 from 20 C. to 21 C.). For smaller measurements the small calorie 



* As this force varies, owing to the shape of the earth being greater at the poles 

 than at the equator, the unit known as the "erg" is now employed in exact work. 

 This is the force which will impart to a resting gramme-mass a velocity of 1 centi- 

 metre per second. One kilogramme-metre equals 980,000 ergs. 



