22 Mr. C. H. Lees on 



and assuming the temperature of the bar to be constant 

 throughout, we can put (i) in the form 



where f(v) is a function of v determined by experiment to 

 be of the form hv^ where h and n are constants. If the 

 temperature of the surrounding air is not constant the 

 equation takes the form 



cw^ = - myp — V) 



where V is the temperature of the air. 



Multiplying both sides of this equation by ^/ and integrating 



we have 



t. 

 cmj ^ ' 



v-v^== / (v-YYdt 



to 



where v^ is the temperature at time t^ 



The following table gives the mean result of three 

 experiments : — 



