Montpelier examiner. [volume] (Montpelier, Idaho) 1895-1937, 1912-01-19
THE GENERATION AND APPLI-
CATION OF ELECTRIC POWER
BY ARTHUR JoBsoN

of power is called horsepower Here
after 1t will be abbreviated III. PD,
and is equal to $4,000 foot-pounds of
work accomplished in one minute, or
$50 foot pounds of work per second.
Experiments have shown that one
good, strong horse is capable of doing
about $4,000 foot-pounds of work per
minute without seriously over exert
ing itself. Hence the name of horse
power for the unit of mechanical
power
If man raises the SO pound weight,
previously mentioned, to the height
of five feet in two seconds he has de-
veloped u little less than one-quarter
of H. P. We have already seen
that in doing this has accomplished
250 foot-pounds of work. However,
since he does the 25O foot-pounds of
work in two seconds he is working at
the rate of l25 foot-pounds per sec
ond. But there are $50 foot-pounds
of work per second in each H. p.
AhOANiotV Al VIZ OlNiuS LEO Dy OoU W.T.
will obtain the III. P. developed which
when carried to the third decimal
place, actually figures 0.227 H. p.
! We have seen that II span OF horses
exert IA uniform pull of 300 pounds OH
loaded wagon for distance of one
mile they accomplish 1854, 600 foot
pounds of work. Suppose they travel
this distance of one mile in 20 min
utes, how much power are they gen.
Grating? II the horses do 1,584, 600
foot-pounds of work in 20 minutes
evidently they are doing work at the
rate of 79,200 foot-pounds per minute.
81, 900 foot-pounds of work per min
ute is equal to one Fl. p. Therefore.
IL we divide 70, 200 by $4,000 we will
obtain the power developed, which
in this case is equal to "a H. P.
/ We have assumed that certain
steam engine will draw cage weigh
ing 2g00 pounds out of shaft 500 feet
deep. In doing this the engine does
l.000, 900 foot-pounds of work. Sup
pose the engine accomplished this
work In one-half minute. 1t would
then be doing work at the rate Of
100000 foot-ponnds per minute. d.
wiling 10000 by $4,000 (the number
of foot-pounds per minute in each II.
P.) we obtain approximately 60.8
This is the number Of Fl. p. the steam
engine would be developing, and il
we wished this engine to constantly
perform this task 1t would require a
normal rating of about go ii. p. II
we were satisfied in taking two min
utes of time for hosting the cage out
' of the shaft rather than one-half min.
ute, we would require an engine hav,
. ing normal rating of only about II
II. p. The normal rating of an en-.
gine Tor any machine used for gener
! ating power) is the quantity of powe
which 1t will generate most efficient
ly, but the reader must bear In minG
that when an engine is running 1t i
: not always developing it's full ratet
e load. A 10 II. p. traction engine belt
ed to a threshing machine may q
3 times generate 80 per cent more thai
t its rated load, or 225 III. p. The
j again 1t may not develop more tha
. two or three Fl. p, depending npo
Z whether or not the machine Is runnin
,, light or is being crowded with a larg
: quantity of grain.
{ !, The following general rules will b
: given for finding the number of II.
developed in any particular cast
knowing the total quantity of wor
D. done, and the time of doing the worI
n If the time Is given in minute
'k multiply the time by $1,000 and d
le vide the total amount of work dor
'te by this product. If the time is give
N- in seconds multiply by $50 and divid
In the quantity of work by the produ,
Iit tContinled On last page