MECHANICS. o9 
syphon, the short leg resting upon this bottom. Pouring water into the 
vessel, so that its surface is a little below the inside of the curvature 8, 
then in an erect position of the vessel the water cannot flow out; in an 
inclined position, however, as in drinking, this will immediately take place ; 
the long arm of the syphon becoming filled and allowing the escape of the 
water. The same occurs in the drinking vessel, jig. 58, when inclined 
towards the left side. 
In the first vessel the syphon lies concealed in its double wall, and the 
short leg has a small opening only at the floor, while the height to which 
the water is to be filled, and the point to which the water is to be applied, 
are accurately indicated. In the second vessel the construction of the 
double wall itself forms the syphon, and in this case the point to which the 
tongue in the double wall rises, and which must not be exceeded in filling, 
must be marked on the inside of the cup. In both cups the water runs 
into the lower division, whence it must be removed before the experiment 
can be repeated. | 
Finally, pl. 18, fig. 60, represents a very ingenious and amusing appa- 
ratus depending in principle upon the syphon. The principal part consists 
of a vessel divided into three compartments by a horizontal and vertical 
partition, one below and two above. Through the horizontal partition 
pass two tubes; a third passes through the covering of the upper division 
to the left, and at the same time through an open cup, into which a hollow 
bird, 2, inclosing a concealed syphon, dips its bill. Filling now with water 
through the proper apertures, the upper apartments f and c, which, how- 
ever, must not reach the upper opening of the tube at e, this water passes 
from the right hand compartment through the tube d into the lower cham- 
ber; the air displaced escapes through the tube at e, presses upon the water 
in the upper left chamber, and causes it to pass out in a jet through h, and 
to fall into the inclosing basin. As the air in the right chamber becomes 
rarefied by the depression of the water, the syphon at g is filled with water 
by atmospheric pressure upon the water in the basin; this then passes as 
if drunk by the bird, through the tube g down to ¢ again. 
Hero’s Ball, fig. 61, consists of a strong well closed vessel, v, partially 
filled with water, in which at j a piece of thermometer or other fine tube, 
t, with a fine opening, passes through the stopper @ nearly to the bottom of 
the vessel. If the air in the upper part of the vessel is compressed, as by 
blowing in air from the lungs, or if the air above the water is expanded by 
heat, the pressure of the air forces out the water in the form of a vertically 
ascending stream. 
The intermitting spring (jig. 62) consists of a water vessel, 7, with 
escape tubes, j, 7, and a tube, ¢, whose upper end projects above the surface 
of the water at 7, while the lower, which has a small notch in it, stands ina 
vessel, p. When the notch is free, the pressure of the atmosphere upon the 
surface of the liquid in r, causes this to flow out through the tubes 7, 7, into 
the vessel p. Assoon as the lower end of the tube ¢ is covered by the water 
pouring into p, the discharge through j, 7 ceases, because no more air can 
pass through ¢ into the vessel r. In the meantime, however, the water 
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