THE LAW OF RESISTANCE IN PARALLEL CHANNELS. 
9G1 
Table II. 
No. of Gauge. 
Readings on 
Gauge. 
Time. 
Quantity. 
Coefficient. 
Logarithmic 
coefficient. 
Seconds. 
C.C. 
Gauge No. 1 
ib. 
1955 
61 
59 
1160 
1160 
j -966 
1-985 
No. 2 
5-3 
54 
1160 
4-055 
•608 
ib. 
15-3 full 
— 
A 
4-055 
— 
No. 3 
15 
360 
A 
16-220 
1-210 
No. 4 
15 
178 
A 
32-440 
1-511 
No. 5 
15 
90 
A 
64-880 
1-812 
From this table it will be seen that the absolute values of the coefficients were 
obtained from experiments on the gauges No. 1 and No. 2, the coefficients for the 
gauges 3, 4, and 5 being determined by comparison of the times taken to fill a vessel 
of unknown capacity, which stands in the Table as A. The relative value of these 
coefficients came out sensibly proportional to the squares of the diameters of the 
apertures. 
For the smaller velocities it was found that the gauge No. 1 was too large, and in 
order not to delay the experiment in progress, two glass flasks were used : these are 
distinguished as flasks (1) and (2); their capacities, as subsequently determined with 
care, were 303 and 1160 c.c. The discharge as measured by the times taken to fill 
these flasks are reduced to c.c. per second by dividing the capacities of the flasks by 
the times. 
28. The method of carrying out the experiments .—This was generally as follows :— 
My assistant, Mr. Foster, had charge of the supply of water from the main, keeping 
the water in the pressure gauge at a fixed level. 
The tap at the end of the tube to be experimented upon being closed, the zero 
reading of the gauge was carefully marked, and the micrometer adjusted so that the 
spider line was on the division of water and fluid in the left hand limb of the gauge. 
The screw was then turned through one entire revolution, which lowered the spider 
line one-fiftieth of an inch ; the tap at the end of the pipe was then adjusted until 
the fluid in the gauge came down to the spider line ; having found that it was steady 
there, the discharge was measured. 
This having been done, the spider line was lowered by another complete revolution 
of the screw, the tap again adjusted, and so on, for about 20 readings, which meant 
about half an inch difference in the gauge. Then the readings were taken for every 
five turns of the screw until the limit of the range, about 2 inches, was reached. 
After this, readings were taken by simple observation of the scale attached to the 
gauge. In taking these readings the best plan was to read the position of the mercurv 
or carbon in both limbs of the gauge, but this was not always done, some of the 
