August, I9II 
pressure can be provided. As might be supposed, a per- 
fectly tight air-tank will cost more than one only tight 
enough to restrain water. A pneumatic tank, made by one 
of the most prominent makers, is said to cost about the 
same as an ordinary elevated tank with steel tower. It may 
be located below the frost line, thus at once eliminating the 
possibility of freezing. 
A further reason for great elevation or a severely com- 
pressed cushion is to get pressure to accomplish filtration. 
A little consideration should make it clear that effective 
rapid filtration will require strong pressure, since a properly 
made filtration bed will probably set up considerable resist- 
ance to the passage of water. Of course, if the water is so 
pure that no filtration is necessary, then this additional pres- 
sure requirement will not have to be taken into account. 
The pneumatic system is by no means in the experimental 
stage. It has been thoroughly tried out and its effectiveness 
demonstrated. One firm is prepared to supply tanks as 
small as six feet in length and two in diameter, containing 
ninety gallons, exclusive of air cushion, and is prepared to 
furnish tanks as large as forty feet long and nine feet in 
diameter, having a capacity of 19,000 gallons. If a greater 
storage capacity is needed, several tanks may be connected. 
Another manufacturer constructs tanks up to 15,000 gallons 
capacity. The 19,000-gallon tank, when two-thirds full of 
water, would weigh considerably over 105,000 pounds. 
Having a supply of water, a tank, a pump, and necessary 
piping, there yet remains the question of power. There are 
the windmill and the hydraulic ram; there are the gas engine, 
the gasoline engine, the hot-air engine, the electric motor, 
and the steam engine. The conditions of individual cases 
of most suburban and country houses will eliminate one or 
more of these at once. Ordinarily, there will not be many 
to choose from. Thus special topographical conditions are 
necessary before a ram can be considered. Where it is pos- 
sible to use it, however, it is probably the cheapest method. 
The first cost is not great, there is but little in the way of 
repairs, and the power itself usually costs nothing. With 
the windmill there is no expense for power; the same can 
hardly be said, however, as to repairs and upkeep in gen- 
eral. There are times when water is wanted and no wind 
is blowing. This difficulty can probably be pretty thoroughly 
overcome by having a sufficiently large tank. The fact that 
the wind blows at no expense is a powerful argument. If 
one lives near a trolley line and can arrange with the man- 
agement, or in a district covered by a company distributing 
the electric current, then an electric motor may be the thing. 
Such an apparatus is simple to operate; the first cost is not 
great; it is compact, clean, and can be depended upon for 
AMERICAN HOMES AND GARDENS 
289 
instant service. The cost of the current will vary in different 
sections of the country; it will sometimes vary with the time 
of day when the power is used. ‘Thus, if the current is used 
in the earlier part of the night—say from 8 to 12 o’clock— 
a higher price may often be expected because of the de- 
mands for lighting purposes at that time. Conditions sur- 
rounding the water supply may be such that the householder 
can do his pumping at an advantageous time, and thus secure 
a low rate. All this should be remembered in considering 
an electric motor. The cost of its operation may turn 
largely on the time of day it is used. He must also consider 
any dangers that may arise from the use of a heavy electric 
current. With the most up-to-date safeguards and arrange- 
ments, dangers to life and property are minimized. The use 
of a gas engine will turn largely on the accessibility and cost 
cf a supply. Evidently, economic conditions are much dif- 
ferent in a district where natural gas is available, at thirty 
cents or less a thousand cubic feet, from what they are in 
one where the manufactured article, at $1.00 per thousand 
feet, is the only possible supply. However, even where the 
gas itself is expensive, some other conditions may so control 
as to throw the choice to the gas engine. The gasoline en- 
gine is a very good piece of apparatus. The reservoir 
should, of course, be located at a distance from the engine 
and in a situation where the ill results of an explosion are 
minimized. The hot-air engine is an old and well-tried de- 
vice. ‘his is extremely simple in operation and is probably 
economical for small installations. The only direct expense 
in the production of power is for fuel and attendance. There 
are, in one of the prominent types, two vertical cylinders in 
which pistons move up and down. In the one, air is com- 
pressed; in the other compressed air is heated. The com- 
pressed air finds its way from the compression cylinder into 
the heating cylinder through a device known as a regenera- 
tor. The effect of heat on the compressed air is to give it 
great expansive power; this expansion is what drives the 
engine. The heating is done by means of a stove envelop- 
ing the heating cylinder. The stove may be run by kero- 
sene, gas or anthracite coal. An idea of the expense can be 
gained from the following estimate of the makers: An en- 
gine able to lift 350 gallons per hour to a height of fifty 
feet will consume twenty cubic feet of gas, two quarts of 
kerosene or three pounds of anthracite coal per hour. An 
engine able to lift ten times as much water to the same 
height, in the same time, will consume 100 cubic feet of gas, 
five quarts of kerosene or seven to eight pounds of anthra- 
cite coal per hour. The steam engine is another solution 
of the power problem. Where the amount of work to be 
performed justifies, it is ordinarily economical. 
