HYDRAULICS. 
to D A, or D B, for its radius. Now the 
water will, as it flows from D, describe a 
parabola, and will fall upon the line, A F, at 
such a distance from A, as will be equal to 
double the radius, D G. In like manner the 
water flowing from the aperture, C, will 
reach that point, vis. K, on the horizontal 
A F, which may measure double the sine, 
C H, on the same semicircle : and the sine 
of the arc taken opposite to E, i. e. E L, is 
equal to the sine, CH, the water rushing 
from E will intersect, or meet, the water 
falling from C, at the point K. It is to be 
observed, that the parabolic curve of the 
water proceeding from C to K, has a greater 
tendency to gravitation than that issuing 
from E, which rushes with far more force, 
and consequently has a greater tendency to 
an horizontal direction. For the aperture 
at C is only acted upon by a column of one 
foot deep, i. e. from B to C, but the column 
of water from B to E measures seven feet. 
We have already stated, that the velocity 
is equal to the square root of the column's 
height above the aperture. 
It is the peculiar property of fluids to 
preserve their level, notwithstanding any 
varieties of course, or inequality of eleva- 
tion. Thus, supposing the pipe, A B C D, 
tig. a, to be bent into the form required for 
passing over declivities, as shown : the wa- 
ter will rise to the height, A D ; but where 
the channel exceeds the level of that line, 
there will be a break in the course of the 
fluid, such as appears at B : yet the course 
may descend to any depth as at C, provided 
the pipe be brought back to the original 
height. If either end be in the smallest 
degree lower than the other, the water will 
sink to the level of the lower retaining 
brim.. And if the supply be continual, the 
water issuing from the lowest end will 
mount nearly to the level of the source. 
This is the principle on which fountains are 
in general found. To effect this, however, 
the pipe should be small, so as to contract 
the issue of the fluid, and to give it greater 
velocity, by causing it to expose a smaller 
surface for the air to press upon. This con- 
traction should not be carried to excess ; 
else the water would want force to pass 
through the atmosphere, and, being sub- 
dued, wmuld break into drops, and fall 
without gaining any height. The conduit- 
pipe is. usually made about five diameters 
of the fountain-pipe ; under such propor- 
tions the water will ordinarily flow so freely 
as to give a good jet. 
The inelastic nature of water causes it to 
retain its surface perfectly level; were it 
otherwise, vessels would often run aground 
where, at present, they find depth sufficient 
to float them ; and the whole body of a ri- 
ver would present a thousand opposing and 
unequal resistances; whereas we find the 
resistance to be uniform. To prove this, 
let a piece of wood be put into a pail of wa- 
ter, the fluid will in every part remain 
equally dense, and the surface will be per- 
fectly level. For a further elucidation of 
this property, we refer to Hydrostatics, 
wherein it will be found very conspicu- 
ous. 
The ingenious Mr. Bramah has lately ap- 
plied the inelasticity of water to a variety , 
of purposes, especially in the application of 
a power to remote effects. Thus, if water 
be filled into the pipe, A B C D, fig. 3, 
and that a piston be applied to A B, made 
perfectly tight, so that no w-ater can possi- 
bly escape, when that piston is pressed 
down by means of a force capable of over- 
coming the friction of its sides, and the 
friction of the water within the tube, it will 
cause the water to rise in the pipe, C D, 
whatever may be the length of the conjunc- 
tive part, A C. Therefore, if a piston is in- 
serted into the pipe, C D, it will be acted 
upon in perfect conformity with the motion 
of the piston in A B ; the power to move 
which may be trifling, when the diameter 
of the pipe is small, and the purpose not 
relating to forcible operations. Thus, for 
the mere intention of ringing h bell at ,D, 
a hundred yards distant from the pull, A, a 
bore of less than a quarter of an inch in 
diameter would answer every purpose, and 
would yield to the pressure of the finger, 
with very little exertion. On the other 
hand, when machinery is to be set in motion, 
the size of the piston, and the force where- 
by it is to be moved, must be proportioned 
to the resistance generated by friction, and 
by the opposition to the action of the ma- 
chine. It is necessary to observe, that 
where the two pistons are of equal diame- 
ter, their actions will be equal ; but that if 
the pipe, A B, be larger than C D, it will 
produce an increased action in the latter, 
which, in such case, must have a propor- 
tionate increase of altitude, and, vice versa, 
when the action of A B is to be greater 
than that of CD. Our readers will be sen- 
sible that a tube of less diameter can be 
made to contain the same quantity as that 
of greater capacity, only by adding to its 
length ; and that ^oth their areas being 
filled and emptied alternately by the same 
