This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
The homemade siphon shown in the sketch consists of two rubber corks and a glass tube with a rubber hose connected to it. The cork A is used as a bearing and support on the edge of the tank. The position of the cork B on the tube determines the distance that the mouth of the tube will be under the surface of the liquid, also to some extent the sensitiveness of the apparatus. However, the principle of the device is the buoyant effect of the water and the lever action of the rubber tube which is attached.
Ill: The End of the Pipe is Kept Just under the Surface of the Liquid at all Times
The one that I made had a tube 14 in. long, and the cork B was 1 3/4 in.in diameter, 1 in. thick, and weighed about1/10 of a pound. The practical application of this siphon will be found in sieve tests where it is necessary to collect the residue on the bottom of the tank while drawing off the liquid at the surface, also in oil-storage tanks where it is not wished to disturb the dirt or other residue which collects on the bottom of the tank. - Contributed by James Hemphill, Jr., Duquesne, Pennsylvania.