ClipArt ETC
"The vertical distance form the level of the upper liquid to the highest point of the tube (ab) is the length of one arm; the vertical distance from the highest point of the tube to the lower end of the tube, or to the level of the liquid into which it dips (cd), is the length of the other arm. The second of these must exceed the first." -Avery 1895

Siphon

"The vertical distance form the level of the upper liquid to the highest point of the tube (ab) is the…