130 
The curve with the arrows pointing to the left is travelled over first. 
We now proceed to give some details as to the current at the 
avis of the tube. The velocity of the water is rather small imme- 
diately after traversing the O-tubes. From /’ onwards the velo- 
city increases continuously, reaches a maximum at D and then 
decreases, after passing a smaller maximum, to about 5830 em./sec. 
After the passage of the horizontal O-tnbe, connecting the two tubes, 
the current reaches A’ with low velocity. This increases to D’, 
decreases somewhat and again increases to /”. From this repre- 
sentation the mean velocity at the axis in the tube first traversed 
is 551,9 cm./see. In the tube with the windows which is passed 
next, the mean velocity is 544,4 cm./sec.') Hence the mean velocity 
over the whole length of 604 em, becomes 548,1 em. (cocks A 
and C’' open). 
If the cocks B and D are open, the water first passes by F”’. 
The velocity changes as%indicated in Fig.£3. Just as in the case 
BanvD OPEN 
VELOCITY 
ST 
. 
oo 
MEAN VELOC! 
sor a= 
500 
450 
first considered the curve with arrows pointing to the left is first travelled 
over, but in order to apply Fig. 1 to the present case the arrows in it must 
of course be reversed. Near /” the velocity is rather great, it 
decreases to MK’, increases to B’ and again decreases, the water 
after traversing the horizontal O-tube arriving in A, with low 
velocity. After attaining to a secondary maximum in A, the velocity 
increases to C and then somewhat decreases. The mean velocity in* 
1) (lt need scarcely be pointed out that the difference between these two 
numbers extremely probably is real.) (Note to the translation.) 
