290 



Mr. Dugald Clerk 



[Jan. 29' 



that at a given time after the moment of ignition the heat loss is 

 much greater when the fan is running than when the gas is at 

 rest ; but this is mainly due to the acceleration of the spread of the 

 flame. The specific effect on the rate of heat flow produced hj the 



-4500 a PM 



I 



3600 a PM 



I 

 2300 a.PM 



FAN AT BEST 



PRCssuae . iM 



Ae 60 so 



LBS Fca saiN ABOve ATMOSPHCAC 



Fig. 



20. — Effect of Speed op Fan on Rate of Heat-Loss. 

 10 Per Cent Mixtures. 



PRE&SURC . IM LBS PEA SQ "^ 



Fig. 21. — Rate of Heat Loss. 



turbulence is shown in Fig. 20, whence it appears that with a fan 

 speed of 4500 revolutions per minute this rate is nearly doubled at a 

 pressure of 75 lb. per square inch. The added heat flow consequent 

 on turbulence seems to be roughly proportional to the speed of the 

 fan. It will be seen from Fig. 21 that at a given pressure, and with 

 a given speed of the fan, the rate of heat flow from the products of 



