Constant Current Type of Hot- Wire Anemometer. 7 2d 



instance the bridge was balanced in the absence of an 

 impressed flow ivith the wire disposed horizontally, and there- 

 after calibration curves were determined with the wire 

 disposed either horizontally or vertically, readings corre- 

 sponding to the respective horizontal and vertical dispositions 

 being taken alternately for the same value o£ the impressed 

 velocity of the air stream. Similar determinations, were 

 then made with the bridge balanced in the absence of an 

 impressed flow with the wire disposed vertically. The 

 temperature of the wire corresponding to the various flows 



ZOO 300 



OEFLECTiOM 



was determined in the manner previously described. Cali- 

 bration curves were determined employing values of the 

 heating current ranging from 0*9 to 1*5 amp. They all 

 showed the characteristic features of the curves drawn in 

 fig. 5, which gives the results obtained when a heating current 

 of 1*000 amp. was used in the bridge. A difference of 

 1 scale division in the respective deflexions when the wire 

 was disposed vertically or horizontally could be detected 

 with ease. With the exception of the velocity corresponding 

 to the point Q, the points P obviously correspond to a 

 minimum value of the impressed velocity for which the 



