WATER SUPPLY, PLUMBING, ETC., FOR COUNTRY HOMES. 39 
with a valve may be installed below the tank, as shown respectively 
in figures 29 and 28. The discharge chamber should be fitted with 
an outlet set above the siphon which will allow the sewage to escape 
in case the siphon becomes clogged. 
A concrete mixture of 1 part cement to 2 or 2\ parts sand to 4 or 5 
parts of broken stone or gravel should be used in the construction 
of the tank, and it is a good idea to use the oil-mixed method pre- 
viously noted (p. 4) to help to waterproof the concrete. 
THE AUTOMATIC SIPHON. 
The automatic si- 
phon may be installed 
to operate as fre- 
quently as may seem 
desirable. Figure 31 
shows a 3 or 4 inch 
automatic siphon in- 
stalled. The siphon 
operates as follows: 
As the liquid enters 
the discharge cham- 
ber its weight in- 
creases with increas- 
ing depth, and the air 
between the water 
surface in the bell and 
the water inside the 
" siphon leg" is com- 
pressed. As the water 
Out sid P inrrpa qpq in "^ IG * ^' — Tnree - mc h or four-inch automatic siphon installed. 
depth the compression inside becomes greater until the water outside 
reaches the drawing or discharge depth for the siphon. Then the 
inside pressure is sufficient to force the water in the siphon leg around 
the bend, instantly relieving the compression. The water from the 
tank then rushes in to fill up the space which was occupied by the air 
and starts the siphon, which continues until the outside and inside 
pressures are again equalized. 
The following table gives working data and dimensions, as shown 
in figure 31, to be used in installing 3, 4, and 5 inch siphons. Sizes 
of 5 inches and over are constructed a little differently from the 3 
and 4 inch sizes, although the working principles are the same. 
