The Caldwell tribune. [volume] (Caldwell, Idaho Territory [Idaho]) 1883-1928, 1898-03-19
WIndmill Science.

power which is the equivalent Of $4,000
pounds lifted one foot in one minutes
time yielding $4,000 foot pounds. All
windmills are given by the manufact-
urer a certain horse power equivalent,
this capacity being predicted upon what
the windmill is capable of doing in a
wind of twenty miles per hour, and
which is, by the way, good stiff blow,
and by far stronger wind than gener-
ally prevails. A more conservative aver
age upon which to base your calcula-
lions for general purposes, is not to ex-
coed an average of more than fifteen
miles per hour. 1t is here proper to
saw that a windmill of any diameter has
greater or less power as the square of
the velocity of the wind in miles per
hour, and therefore a mill which would
develop three horse power in fifteen
miles per hour would have but one and
one-third horse power capacity when
the wind was blowing at the rate of ten
miles per hour. The square OF 10 is
225, the square of 10 is 100. A mill OF
any diameter will handle a greater or
less quantity Of water as the verricle
height of discharge in feet Is decreased
or is increased; for instance, mill that
will raise 100 gallons of water per min
ute fifty feet vertically, will lift 200
gallons per minute twenty-five feet YER
tically, or the same mill will lift fifty
gallons per minute 100 feet vertically.
A cubic foot of water weighs approx
mately sixty-two and one-half pounds
and contains approximately seven and
one-half gallons, a gallon OF water
weighing about eight and one-third
pounds. 1t will be of great personal
assistance IL you will remember that
the pumping of water is simple me-
chaLical problem, and acquire the
habit of reducing the quantity OF water
to be handled to so many foot POUNDS
If you will do so it will save you Iroin
serious disappointment. Perpetual mo
ton has not yet been discovered. He-
member above all things one pound OF
any substance, no matter what SUP
stance, lifted one foot vertically IN one
minutes time, or equivalent, requires
a mechanical force of one foot plus
the friction which is due to the means
employed. You can lift yourself over
the fence by your boot tops Just as
easily as you can get away from TINS
fixed law. A great deal is said to-day
nv various persons concerning their
ability to eliminate friction, and that
by this means, or that means they can
discharge a given number OF gallons Oh
water per minute given NUMBER Oh
feet vertically with less power that can
he done bv any orher means OF exactly
the same principle in every detail. II
ought not to take any person long 10
make I'm his or ker mind than the per
son making any such statements de-
liberately deceives himself to say the
least. Along this same line OF thoushC
it is proper to state that exaggerated
ideas prevail to what can be accom-
plished by the wind for various power
purposes. The pressure of the atmos-
phere at the sea level is but 14.7
hounds per square inch. When the
wind is blowing at velocity OF twenty
miles per hour, such a wind exerts
pressure of but two pounds per square
foot of surface exposed. Therefore the
power of windmill is necessarily lin
tied by the velocity of the wind and for
this reason windmills can be used for
pumping water for irrigation or other
purposes demanding large volumes OF
water to but limited extent, and in all
instances where Windmills are utilized
for this purpose they can be success
fully used only in connection with res
erVoirs of ample capacities.
An. acre of ground contains 6,272, $40
square inches. If one acre of ground
be covered with water one inch deep,
we would have quantity of water
equaling 27,155 gallons or what is
termed one acre inch. If the quantity
Of water on the one acre be increased
to thirteen inches, we would have what
is called one acre foot, or $50 cubic
feet or S25,851 gallons Of water. 1t is
conceded that in the semi-arid belt one
foot of water per acre is necessary to
insure the growing, and it seems to be
established that this quantity Of water
will be demanded principally in two
months Of the season. To irrigate ten
acres Of land requires, therefore, to-
tai of 3,258,510 gallons of water, and If
all is applied in the two months, it re-
quires an average of 1,625,25O gallons
per month. Assuming that windmill
will work to its full capacity, ten hours
per day, thirty days per month, we
would then need for the ten acres of
ground an average Of 5,431 gallons per
hour, or 81 gallons per minute, or lilo
mi AGGnm-
ing that this quantity of water must