[Illustration: Diagram of apparatus as described in text]
The “fountain” as it is called may be made to trickle as long as the
sun falls upon it. Let there be an air-tight pedestal, A B C D (fig.
47), through which a funnel is inserted, its tube extending within a
very little of the bottom. Let E F be a globe, from which a tube leads
into the pedestal, (reaching nearly to the bottom of the pedestal and
to the circumference of the globe,) while a bent siphon, fitted into
the globe, leads into the funnel. Now pour water into the globe; and
when the sun falls upon the globe, the air in it, being heated, will
drive out the liquid, which will be carried along the siphon G, and
pass through the funnel into the pedestal. But when the globe is in the
shade, the air having escaped through the globe, the tube will again
suck up the liquid, and fill the void which had been produced; and this
will take place as often as the sun falls upon the globe.