FOUNTAIN. 
fn the weffe : where it preffce againit the water {pouting am 
at B with jth of the force by which the water is pufhed 
up at the hele A, by the preflgre of the common air on the 
water in the veffel -A ; fo that the water fpouts up into E, 
wihen the air is paeeed ts» with the difference ofthe preffure 
‘of the atiniofphere, and the pl ane rarefied air; ¢. e. 
Thi is would. raife’ th 
pipe A, nine inches being 
the jet will-only rife two feet. ‘I'his, fays Defa- 
‘guliers, may a called.a fyphon ue where A B is the 
ea hei and C D the iffuing 
AIN ees o of Alexandria, fo called, becaufe it was 
c ‘enue aa ae . Inthe firft fountain already defcribed, the 
‘air is core ed by a fyringe ; in this, fee fig. 5, the air, be- 
ing only comprefied by the concealed fall of water, makes 
a jet, which, after fome conthmance, i8 s confidered. by the 
t that — does net come again; for it runs 
ae x into the box D Y ».¢ from 
ing the pipe 
into the cavity ee the jet" is 
proportional to the are of Pah, pipe Ww X, or of the 
xes C E and D Y above one another; the height of the 
‘water, meafur ed from the bafon 
ac C BE. Now 
furface C E is oe bs pagar and the water in D Y always 
rifing; the height e 
it is thorter by thecheight of the depth of th 
which is emptying, added to the depth of die ere DY 
which is always filling ; and when the jet is fallen fo low 
it immediately ceafes. The air is reprefented by the points 
in this figure. To prepare this fountain for playing, which 
fhould be done ay d, pour i tll aa 
‘cavity D X Y is filled-; then invert: the. Panta ‘and t 
water will run on | cavity D X Y into the eavity C E, 
which may be known to be full, when the water runs out 
at B held down. - Set ihe fountain up again, and, in order 
a make it play, pour in about a pint of water into the bafon 
A BW; and as foon as it has filled the Pipe, Ww X, it will 
begin to play, and continue as long as ther 
as you plea 
~The fountain, jg. 6. is of the fame. ads ‘but = 
double the number of ee and concealed cavities, it plays 
as high again. In order to underftand its ftruéture, fee fg. 7. 
~The baion is A, the four cavities atte C,"D, and E, 
which the water through the pip 
which. falling oo conga ayer: m C to D, is Guile by 
“the height of its fall, of condenting thovir at E,. fo: as 
water two. feet nine former 
A B W to the furface of - 
t mutt continually — «al 
vity CE 
. Sar ts the 
ake it ra Rronger, being pufhed at c ‘by air already — 
tend i vn lefs {pace, caufes the air at E to be cone 
denfed.twice ea much ; that is, to be.+ ftronger than ‘come 
mon air; and, therefore, it will make the water at G {pour 
out with twice the force, and rife twice as high as it would 
do, if the’ fountain had been of the fame ftructure as the 
In pla yit ig t l 3 turf it 
taking out the plugs g, h, ‘il the 
and, having fhut the holes again, fet the fountain, upright, 
and pour (ne send into the bafon A, and the jet will play 
out at G e fountain will begin to play too foon 3 
and, xii Na ne beft way is to have acock in. the pipe 
3». which, being open, whilft the cavities C and E are filled, 
and fhut again before the fountain is fet up, will keep the 
water thrown into the bafon from going down the Pipe, Ty 
and that of the cavity C from going down the pipe 3, by 
which means the vee will t play belo its time, which 
will be as foon as the c 
Fountain, Dial, 0 ie De ee is contrived to play 
by the {pring of the air, increafed-b heat of the fun, 
and ferves alfo for a dial at the fametime. G NS, ve By 
is a hollow globe of thin copper, eighteen inches in diame- 
ter, {uppor ted by a {mall inverted bafon, refting on a frame 
ABC, with four legs, between bees ie is a large 
a of two feet diameter. In a leg C there is a con- 
e bottom fi thei infide 
oe making a jet a at » going t 
ae of the bafon, has a valve at u, ander the horizon tal 
V, and another valve at V above it, and under the 
air, fhe air 
condenfes again ‘g the cold, the outward air, preffing into 
the ajutage I, will fhutthe valve N, but by its preffure 
on the bafon D u ufh up the water, which has been 
played inthe day-time through the valve u, the pipe 
HG into the globe, fo as to fill it up again to the fame 
height which it had a : n-fhine will 
_The ufe of the cock 
a {mall ist ill sey fix or eight hours. 
fet for the. latitude of the i and webtified bie it be 
n the a 
thin ning u the fame ee in this globe as it does upon 
the earth ‘felf. 'Delaghliens Exper. Phil. vol. ii. leét. 9. 
20 
AIN,. with regard to Architedure, is an af. 
femblage of mafonry, fculpture, &c. either for the decora- 
tion, or conven iency ofa city, garden, or the like. 
Fountains acquire varieus denominations, according to 
their form and fituation.; 
T ed, ae whofe bafon and jet are 
placed ahaa ia iit under the arch. Such are the foun- 
Colonade, -and the triumphal water-arch at 
Fouwratn, Bafon, is that with only a fimple bafon of 
re: whatever; in the. middle whereof is a jet or 
ee is or perhaps a flatue, or even a group of: ask 
puc 
Ss 
