596 
DE. VIKTOE YON LANO ON THE 
stance, which is of great influence in regard to the absolute values of the volume of 
air, may be neglected in the present research. The result of these experiments is that 
the quantity of the aspirated air approaches to a maximum with the length of the tube. 
The maximum itself could not be reached exactly, even with the smallest tubes ; but 
this arises certainly from the conical form of the water vein ; for within certain limits 
the volume of the air increases when the vein becomes smaller, the quantity of the 
water remaining constant. The following Table gives the numbers found by these 
experiments, the quantity of water discharged being equal to 20 gallons. A is the 
volume of the aspirated air, l the length of the aspirating tube, and ft its radius, found 
by the weight of mercury filling up the tube. The latter two quantities are given in 
centimetres, and A in cubic centimetres. 
Asp. tube. 
E. 
l. 
A. 
. 
0-254 
47-2 
17-1 
38-2 
16-6 
26-0 
15-1 
16-0 
14-0 
2 
0 288 
47-1 
22-3 
37-3 
21-8 
26-5 
19-1 
3 
0-383 
49-8 
28-1 
42-6 
25-8 
36-5 
22-6 
4 
0-435 
50-5 
25-2 
44-0 
23-1 
31-7 
17-5 
The numbers given for A are not directly observed ; but at first the mean was taken 
of all readings for A above and below W=20, and then the required quantity was 
interpolated between these two means by simple proportion. 
For the tubes 1 and 2 the diminution of the volume A is very small, although their 
length decreases by 10 centimetres. The tubes 3 and 4, on the contrary, seem to be 
by far too short to give the maximum of A. We may therefore say that an aspirating 
tube 47 centimetres long, W being equal to 20 gallons, gives the maximum of air only 
when its radius is below 029 centimetre. 
The second series of measurements were executed in October of the same year with 
the aspirating tubes 5-9, all of them 48 centimetres long, and with the measuring tubes 
II.-VL The values of A found by these different tubes are given in the following 
Table. There exists no material difference between the numbers found by the tubes 
II. and III.; even the coupling of these two tubes did not produce larger volumes. 
For the following calculations the mean was therefore taken of the values II. and III., 
and the numbers so found are given in the last column. 
