62 Proceedings of the Royal Society of Edinburgh. [Sess. 
and the purely viscous loss was calculated from Poiseuille’s value 
of ju, viz., 
•0000181 
^ 1 + -03368* + -00022 W 
Three tubes were used, of the following dimensions : — 
Tube. 
Diameter in cm. 
Length. 
Cm. 
Ratio 
external 
Internal . 
External. 
internal 
diameter =m. 
A 
*0715 
•1073 
4-29 
1*50 
B 
*1470 
*1960 
6-66 
1*33 
C 
*2580 
•9000 
38*20 
3*50 
For tubes A and 13, £=14-2° C., making [x= *0000119. 
For tube C, £=12*9°C., „ /* = *0000123. 
Since the pressure in the interior of the jet at the point of discharge 
T 
is greater than atmospheric by an amount — , where T is the surface tension 
and r the radius of the jet, the effective head is less by this amount than 
the measured head. 
Thus, for tube A, T = *073 grms. per cm. ; — = 2*028 cm. 
r 
„ B, T = '073 „ ; 1 = 1-00 „ 
r 
„ C, T = -075 „ ; 1=0-57 „ 
r 
This correction is applied in the following tables, which give the 
experimental results. 
Tube A. 
Loss of head in cm. 
v 2 
Experiment. 
Total. 
In viscous 
resistance. 
Due to T 
at outlet. 
Residue 
(-*©■ 
V 
c. per sec. 
L 
1 
16-50 
12-400 
2-028 
2-072 
39-00 
•775 
2-68 
2 
16-22 
12-200 
55 
2-002 
38*40 
*750 
2-68 
3 
8-48 
5*980 
55 
0-475 
18*82 
*1805 
2-63 
4 
8*35 
5*870 
55 
0*452 
18-48 
•1740 
Mean = 
2-60 
2-65 
