On a New Electrometer (the Siphon-Electrometer). 453 
about 3 inches diameter, connected with the ground by a damp 
cord, and placed directly below the orifice G of the tube, and 
connected with a glass tube, K L, divided into tenths and hun- 
dredths of a cubic inch; N P a conducting wire fixed to the prime 
conductor of the electrical machine and dipping into the liquid 
EF. The instrument is used in the following manner :— 
A sufficient quantity of water is poured into the jar, so as to 
cause the siphon to act; the water then flows through the siphon 
until its pressure in the jar is balanced by the capillary action of 
the tube G E, when it will cease to flow; it will then be found 
that the level of the water in the jar stands somewhat above the 
orifice G of the siphon-tube: scarcely any amount of shaking 
or oscillation will now cause the water to flow from the orifice G. 
The graduated tube K L is then placed below the orifice G, the 
bottom of the funnel being from 24 to 24 inches from this orifice. 
The machine is then turned, and the electric action causes the 
water to flow in a continuous stream or jet from the orifice G, 
filling the tube K L; any proposed number of revolutions being 
given to the machine in a known time, the number of cubic inches 
of water discharged is taken as the measure of the efficiency of 
the machine. 
It will be hereafter shown, the machine being in a fixed state 
of action, that in order to produce a given or constant discharge 
of liquid, the product of the number of revolutions of the machine 
by the time in which these revolutions are made must be a con- 
stant quantity. Thus, if revolutions, performed in ¢ seconds, 
produce a discharge of & cubic inches of water, and n, revolu- 
tions, performed in 7, seconds, produce the same discharge of 
liquid, then nt=nty. 
Hence it follows that (within certain limits) the relative effi- 
ciency of a machine (in different states of action, or of different 
machines) will be inversely as the product of the number of revo- 
lutions by the time requisite for producing a given or fixed 
amount of discharge. Thus, if a machine discharges one-half of 
a cubic inch of water in 20 revolutions per 60 seconds, and another 
machine discharges the same amount of water in 15 revolutions 
per 40 seconds, then the powers of the machines will be as 
1 ‘ 1 
20x60 °° 15 x 40 
The following results of experiments show the uniformity of 
the action of the instrument. 
24 revolutions of the machine, in 45 seconds, produced a dis- 
charge of °61 of a cubic inch of water ; and the experiment being 
repeated for two successive times, the discharges were found to 
be 62 and ‘61. 
wor asl tO 2: 
