560 



The above Table shows an increase of temperature nearly pro- 

 portional to the square of the velocity. 



275 

 01026 = 163' 7 = the velocity in feet per second, which, 



in air of the same density, would have raised the temperature 

 1 Centigrade. 



/ 



= A / - 



TABLE II. Larger bulb Thermometer. 



Velocity in feet Rise of temperature in Rise divided by 



per second. divisions of scale. square of Telocity. 



36-3 ............ 18 ............ -0125 



66-6 ............ 42 ............ -0095 



84-8 ............ 57 ............ -0079 



125-6 ............ 146 . . . . ........ -0093 



Mean.. -0098 



/ 330 



In this instance V= \/ ^QO^= 183'5 feet per second for 1 Cen- 



tigrade. It is however possible that the full thermal effect was not 

 so completely attained in three minutes (the time occupied by each 

 whirling) as with the smaller bulb. On the whole it did not appear 

 to us that the experiments justified the conclusion, that an increase 

 of the dimensions of the bulb was accompanied by an alteration of 

 the thermal effect. 



TABLE III. Larger bulb Thermometer covered with five folds 

 of writing-paper. 



Velocity in feet Rise of temperature in Rise divided by 



per second. divisions of scale. square of velocity. 



36-3 ............ 20 ............ -0152 



51-5 ............ 43 ...... . ..... -0162 



72-6 ____ ........ 53 ............ -0101 



118 ............ 132 .... . ....... -0095 



The increased thermal effect at comparatively slow velocities, exhi- 

 bited in the above Table, appeared to be owing to the friction of the 

 air against the paper surface being greater than against the polished 

 glass surface. 



One quarter of the enveloping paper was now removed, and the 

 bulb whirled with its bared part in the rear. The results were as 

 follow : 



