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.
A simple aspirator that may be used for a number of different purposes, such as accelerating the process of filtering, emptying water from' tubs, producing a partial vacuum in vessels in which coils are being boiled in paraffin, etc., may be constructed as follows : Obtain two pieces of brass tubing of the following dimensions: one 7 in. long and 3/4 in. outside diameter, and the other, 3 in. long and 1/4 in. outside diameter. Drill a hole in one side of the large tube, about 3 in. from one end, of such a diameter that the small brass tube will fit it very tightly. Take an ordinary hacksaw and cut a slot in the side of the large piece, as shown at A. This slot is sawed diagonally across the tube and extends from one side to the center. Obtain a piece of sheet brass that will fit into this slot tightly, and then solder it and the small tube into the large tube. The slot and hole for the small tube should be so located with respect to each other that the small tube will empty into the larger one directly against the piece of sheet brass soldered in the slot.
Ill: Detail of the Aspirator and Its Connections to a Faucet, for Increasing the Speed of Filtration
The upper end of the large tube should be threaded inside to fit over the threads on the faucet, or an attachment soldered to it similar to those on the end of an ordinary garden hose. A rubber hose should be attached to the small tube and connected, as shown, to a piece of glass tubing that is sealed in the cork in the top of the large bottle. The funnel holding the filter paper is also sealed into the cork. Melted paraffin may be used in sealing the glass tube, funnel and cork in place, the object being to make them airtight. The filter paper should be folded so that it sticks tightly against the sides of the funnel when the liquid is poured in, thus preventing any air from entering the bottle between the paper and the funnel. Turn on the faucet, and it will be found that the time required to filter any liquid will be greatly reduced. Be careful, however, not to turn on too much water, as the suction may then be too strong and the filter paper become punctured.