58 
GARDEN SCENERY. 
Water rising from a small jet or adjutage lias sufficient velocity 
to carry it to the same height as the water stands in the reservoir; 
but it never entirely does so, being prevented attaining that 
height from various concurrent causes. These are,—the friction 
in the tubes between the reservoir and the jet; the friction against 
the circumference of the aperture or adjutage; and the resistance 
of the air to the height of water at the top of the spout, and in its 
ascent. Here the water having lost its momentum rests on the 
part below, and by its weight obstructs the motion of the ascend¬ 
ing column—the resistance from this cause being so great, that 
the jet is frequently destroyed, the rising water being by tits and 
starts pressed down towards the very orifice from which it issues. 
This inconvenience is, however, remedied by giving a slight in¬ 
clination to the jet, as the particles which have lost their upward 
motion do not fall back as in the former case, but falling off, 
leave the rising fluid unincumbered. Such jets as have a slight 
inclination will, from this cause, rise higher than those which are 
vertical. In order to make large jets rise higher than small ones, 
the conduit pipe must be large enough to supply a sufficient 
quantity of water, experience having shown that if these are nar¬ 
row, small jets will rise higher than those which are larger. The 
diameter of the conduit pipe must, therefore, have a certain pro¬ 
portion to that of the adjutage, in order to make a jet rise to 
the greatest possible height. 
“ If we compare two different jets, and are desirous that each 
should attain its greatest possible altitude, the squares of the 
diameter of the conduit pipes must be to each other in the com¬ 
pound ratio of the squares of the diameter of the adjutages. 
Thus, if we know by experience the diameter that should be 
given to a conduit pipe, to furnish water for the discharge of a 
given adjutage, with a reservoir of a given altitude, we may de¬ 
termine the diameter of another tube to feed a larger adjutage 
with a reservoir of the same given altitude. Care must be taken 
also that the conduit pipe increases in strength, in proportion to 
the height of the reservoir. Where the water contains much 
carbonate of lime in solution, it is apt to increase and stop up 
the pipe by its deposition ; and whether lead or iron be used, 
carbonates are formed at the expense of the metal, the corrosive 
effects of which are more early visible in the destruction of the 
