There are some vessels which emit no stream unless
they are filled; but when filled discharge all the Iiquid they
contain. They are made as follows: Let A B C D (fig. 12) be a vessel
open at the top, and through its bottom pass a tube, either an inclosed
diabetes as E F G, or a bent si1A'on G II K. When the vessel A B c D is
filled, and the water runs over, a discharge will begin through the
diabetes, and continue till the vessel is empty, if the interior opening
of the diabetes is so near the bottom of the vessel as only to leave a
passage for the water.