[PATTERSON] 



CANADIAN STANDARD ANEMOMETER 



85 



given by the chart, should be constant and equal to -00073^ Table 

 II gives the results of the calibration for the pressure tube used in 



the experiments. 



Table II 



Up = the pressure was increased from the lower to the next higher. 

 Down=the pressure was decreased from the higher to the next lower. 



The calibration shows that in this instrument the factor is not 

 constant below 30 miles per hour and that for values above 30 miles 

 per hour it is 6% higher than that for which the instrument is cali- 

 brated. The density of the fluid in the tank was tested and found to be 

 one. The values in the last column are plotted against the velocities 

 in Fig. 2, and the curve thus obtained gives the factor for correcting 

 the recorded to the true velocity. 



Correction Factor for the Canadian Standard Anemometer 



The Dines pressure tube anemometer was erected on the same 

 tower as the Canadian anemometer. The tower is 40 feet high, and 

 the anemometer and pressure tube are about 10 feet above the top 

 of the tower. They have a free exposure in all directions, being on a 

 narrow strip of land between the Bay at Toronto, and Lake Ontario. 



' The value of — ■ depends on the density of the air and is thus not constant 



but for all practical purposes it can be assumed constant for most places on the earth's 

 surface. 



