506 



Mr. J. S. G. Thomas 



on 



right angles to the anemometer bridge-wires. The heated 

 wire in King's calibrations was attached to a radial arm which 

 was capable of being rotated in a horizontal circle. The 

 wire in these latter experiments was used horizontally, ver- 

 tically, and inclined at 45° to the vertical, respectively. The 

 conditions of calibration in the experiments both of King 

 and of Morris differ essentially from the conditions ruling 

 in the case of the flow of gas in a tube or pipe. The anemo- 

 meter employed in the present experiments is shown dia- 

 grammatical ly in fig. 1, and a transverse section across the 



Fiff. 1. 



tube at the exposed platinum wire is shown in fig. 2. Two 

 fine platinum wires (the one AB exposed, the other CD 

 shielded within a surrounding copper tube) were inserted, as 

 shown, in the tube, through which a current of air or other 



Fio-. 2. 



gas flows. The manner of inserting the wires is best seen in 

 fig. 2. The ends A and B of the fine platinum wire are 

 affixed, by means of the smallest amount of silver solder 

 affording a secure junction, to portions of considerably 

 thicker copper wire AE and BF as shown. These copper 

 wires pass tightly through holes bored through plugs of 

 ebonite K and L inserted into brass tubes joined to the main 

 tube at right angles as shown in figs. 1 and 2. Precautions 



