822 DR. T. R. ROBINSON ON THE CONSTANTS OP THE CUP ANEMOMETER. 
In all the plottings, except that for No. IV., a parabola or straight line, or both a 
parabola and a straight line, are laid down for comparison. The elements chosen for 
these are as follows : — 
For No. L, a= 1 1 '1 83, £= 16'954, y= — 19-862, a' = 9-880, £'=11-538. 
For No. II., a'=2-084, £'= 3-489. 
For No. III., a=9-472, £=8‘469, y=9'814, a'=9'989, £'=10-928. 
For No. V., a=9-152, £= 13-416, y=— 3'481. 
The ordinates of the straight line and parabola were of course reduced in the same 
ratios as those of the dots, giving for the reduced constants in their equations — 
For No. II., a= 10-550, £'=17-663. 
For No. V., a=7-188, £=10-537, y= -2-734. 
PLATE 67. 
Fig. 1. Section of the horizontal arm (paragraph 2). 
Fig. 2. The driving apparatus (paragraph 6). 
PLATE 70. 
Fig. 3. Apparatus for measuring the vortex current (paragraph 13). 
Fig. 4. Brake apparatus (paragraph 21). 
