600 
ON THE EEICTION BETWEEN WATER AND AIR. 
Appendix. 
We have seen that even when we put %=\p=0, the differences between calculation 
and observation are not greater than the errors of observation. We therefore cannot 
expect essential differences when we employ aspirating tubes of other material. This 
was also confirmed by experiments made with two brass tubes. In this case it was 
found a little troublesome to make the jet pass along the axis of the tube, the tube 
being opaque. The radius of these tubes was determined by means of cylinders fitted 
carefully into the tubes ; their length was again 48 centimetres. In the following 
Table the values of A are those found by observation, the values A' those calculated 
by equation (7). 
Asp. tube. 
E. 
W. 
- 
A. 
a '. 
A -A'. 
10 
0*228 
22-2 
0-1461 
14-7 
13-66 
+ 1-04 
24-9 
0-1548 
13-6 
1 12-70 
+ 0-90 
11 
0-270 
19-8 
0-1386 
23-8 
21-69 
+ 2-11 
23-7 
01509 
23-2 
21-14 
+ 2-06 
I have also made a few experiments with other gases. However, no great differences 
are to be expected in this case either, for the reason stated before, as differences could 
only arise from different coefficients of slipping. In these experiments the manometer- 
arm of the crosspiece was used for introducing the gas. In order to get the apparatus 
totally freed from air, the soap-lamina was alternately aspirated by the jet and driven 
back again to the mouth of the measuring tube by introduction of new gas. The 
results obtained are : — 
Asp. tube. 
W. 
A. 
A'. 
Name of gas. 
6 
24-3 
0-1528 
15-2 
16-0 
Coal-gas. 
7 
30-0 
0-1708 
17-0 
17-2 
.» » 
8 
24-2 
26-0 
0-1525 
0-1461 
25- 1 
26- 0 
24-4 
24-0 
Carbonic acid. 
