122 
THE YOUNG SCIENTIST. 
reason for his punishment, and its form, 
but the one from which the common idea 
is derived is tliat of Homer, in wliose 
poem (The Odyssey) Ulysses tells the 
Phseacians that in the lower world he had 
beheld Tantalus standing up to the chin 
in water, which constantly eludes his lip 
as often as he attempts to quench the 
thirst that torments him. Over his head 
grow all kinds of fruits ; but whenever he 
reaches forth his hand to take them, the 
wiiid scatters them to the clouds. 
Our engraving represents the figure of 
liquids from a higher to a lower level, 
over obstacles which would otherwise , 
cause great difficulty, and therefore it is i 
well for our young readers to clearly un- 
derstand the principles upon which it 
acts. 
Two very distinct agencies are always at 
work in the operation of the syphon — the 
pressure of the atmosphere, and the weight 
of the water in the legs of the syphon. In 
the syphon shown in Fig. 2, the column 
of water in the leg, d, is longer, and conse- 
quently heavier, than the column in the 
Fig. 1.— CUP OF TANTALUS. 
Tantalus stooping down to drink the 
water which reaches almost to his lips, 
but as soon as the Avater rises to the level, 
A B, the concealed syphon, c, which is 
shown in dotted lines, begins to act, and 
the water immediately sinks just as it is 
about to rise within his reach. 
The syphon is one of the most useful 
pieces of apparatus that we have, either 
in the hands of the amateur or the profes- 
sional workman. It enables us to transfer 
leg E, and consequently it will overbalance 
it and fall down. 
It is obvious, however, that the column 
of water from e to b is held in its position 
by the weight of the atmosphere pressing 
on the surface of the water in the vessel, 
A. If it were not for this pressure, the 
water in the syphon would separate at b, 
I and fall down each leg, leaving the tube 
empty. But as fast as the heavier column 
in D falls down and escapes from c, the 
