664 



On the Directional Hot- Wire Anemometer. 



0'202 mm. are similarly plotted in fig. 9. It is readily 

 seen that in each case, excluding the range o£ excess 

 temperature above atmospheric from zero to about 150° C, 



600. 



iOO- 200 300 400 500 S00 700 800 900 1000 



Excess Temperature of Wires above Atmospheric (°C) 



the maximum deflexion D m is linearly related to the excess 

 temperature 6. Thus in the case of the wires of diameter 

 101 mm. the relation is 



D m — 0-708 6-4:2, 



and in the case of wires of diameter 0*202 mm. 



B m = 0-538(9-28. 

 The departure from linearity in the relation of D m to for 



