280 Dr. J. S. G. Thomas on the Forced Convection of 



The pressure in the flow tube did not exceed O'l inch of 

 water during the course of the experiments, and at this 

 pressure it was ascertained that there was no appreciable 

 leakage in the flow system. 



In fig. 2 the changes of resistance of the second wire 



! 2 3 4 5 S 7 



VELOCITY (CMS PER SEC, VOLUMES REDUCED TO 0°C and 760 mm.) 



of the pair from its initial value in the absence of flow are 

 plotted as ordinates against the values of the velocity of the 

 impressed stream as abscissae for various values of the dis- 

 tances apart of the wires. For the sake of clearness, only 

 about one-quarter of the experimental points are indicated 

 in the several curves. The calibration curve obtained when 

 the second wire alone was heated is likewise shown in the 

 diagram. For purposes of discussion the various curves are 

 best grouped as indicated by the brackets in the table of 

 distances apart of the wires given in the figure. Considering 

 the first group corresponding to distances apart of the wires 



