1070 dr. T. R. ROBINSON ON THE CUP ANEMOMETER. 
favourable circumstances ; but I think they would make very little change in my 
number. For the portable instrument, the only one of which I have experience is 
Casella’s 3" cups and 6 V arms, and I found it very convenient: its x should be 
determined as above. Some such arrangement seems necessary to ensure a uniformity 
of velocity measures. 
