PHOTO LNG.CO 
Vol. LXVII. No. 3026 
NEW YORK, JANUARY 25, 1908 
WEEKLY, $1.00 PER YEAR 
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A BABY ELECTRIC LIGHT PLANT. 
How a Little Stream Does It. 
Down through our old pasture field runs a brook— 
a very little one indeed. You can generally step 
across it unless the water is fairly high. A little 
more than a half-mile from the house there is an 
old mill dam and a decrepit sawmill. The place has 
been a mill site for generations. There was a grist 
mill there considerably more than a century ago. 
Later it became a busy little woolen mill, with a 
half-dozen operatives, where the farmers 
brought their wool to be made into the 
rough cloth of the time. But 50 years 
ago the woolen mill went the way of so 
many other prosperous rural industries, 
and since then the little stream, first 
harnessed so long ago, has done nothing 
except turn a ruinous old sawmill for 
a few weeks in Spring. But the old 
dam was there still, its banks of earth 
strengthened and held in place by the 
fibrous roots of ancient willow trees, and 
for years as I passed it, I never heard 
the splash of the water over the broken 
apron without being fairly teased by 
it, because I felt there was potential 
energy that for It months of the year 
did nothing but make a little noise. It 
must have been half a dozen years ago 
when I first began seriously to figure 
upon the problem of getting some of 
this power to the house where I could 
use it. My first thought was to carry 
it by means of a wire cable running belt 
fashion upon grooved pulleys—a method 
that is quite practicable for considerable 
distances where large powers are con¬ 
cerned, but a little inquiry and calcula¬ 
tion convinced me that to transmit from 
three to five horse power for 3,000 feet 
in this manner was entirely out of the 
question, both on account of the cost of 
installation and because this amount of 
power would hardly move the cable, to 
say nothing of doing my work at the 
other end. It soon became evident that 
a little turbine and dynamo was the only 
solution of the problem, but there 
seemed to be very little detailed infor¬ 
mation available. I discussed the ques¬ 
tion with every man that I imagined 
could give me any information. 1 
talked with a university teacher of 
electrical science, whose advice appeared 
impracticable. Had I wanted to con¬ 
struct a municipal plant costing a 
hundred thousand dollars, there would 
have been libraries of advice. But a 
plant to furnish a couple of dozen lights 
that must run for a week at a time 
without anyone going near it, and be HO 
controlled by a- wire from a point TOO 
feet distance, offered problems of which the books 
took no cognizance. 
After a good deal of study and feeling my way the 
plans were made. While they have their weaknesses, 
they have no failings that cannot be overcome. They 
would have to be greatly modified to suit individual 
cases, but it seems to me that they ought to be of 
assistance to anyone starting along this line It goes 
without saying that the water wheel must be a tur¬ 
bine. The turbine wheel of to-day is a remarkably 
efficient device for the purpose for which it is con¬ 
structed. They are very compact, not troubled by ice 
or moderate amounts of back water, and properly in¬ 
stalled should run literally by the year almost without 
attention. Under favorable conditions they should 
utilize as much as 80 per cent of the theoretical power 
of the water—a very much higher efficiency, by the 
way, than is attained in fuel consumption by. the best 
steam engine. One most important point must not 
be forgotten if any economy of water is necessary, 
and that is to get a wheel no larger than is needed 
to develop the power required, because a turbine uses 
water with very poor economy at part gate. For ex¬ 
ample, a four-horse wheel at anv given head would 
A COUNTRY POND THAT STORES POWER. Fig. 
W THE WATER FALLS DOWN TO WORK. Fig 
run at full capacity with an amount of water that 
would scarcely be sufficient to run a 10 horse-power 
wheel without load. Turbines make poor use of water 
at half gate, and require a very considerable amount 
even to start them. 
For all small, isolated farm plants the tync of 
dynamo available will be the direct current machine, 
usually of either 110 or 220 volts. Village and city 
plants commonly use alternating machines, but these 
are not regularly built in sizes small enough for 
farm use. Then, too, if power as well as light is de¬ 
sired, the direct current will be much better. If the 
p :wer house j s clqse at hand, it will probably be best 
to select the 110 volt generator, which has the ad¬ 
vantage of rather greater efficiency in lighting, and 
also the fact that lamps and fittings for this voltage 
are more commonly kept in stock by small dealers. 
However, if the power is a quarter of a mile or more 
distant, it will be best to choose the higher voltage, 
because of the great saving that it will allow in the 
cost of the expensive copper line wire—an item that 
is one of the largest in electrical distribution. It 
may be stated, for example, that it will require only 
one-quarter of the copper to transmit a given num¬ 
ber of lights or amount of power at 
220 volts that would be necessary if the 
more usual 110 volt current is employed. 
The small dynamo of to-day as a 
machine leaves little to be desired, 
needing only to be run at uniform 
speed and to have its two bearings kept 
perfectly lubricated in order to furnish 
current for any number of lamps with¬ 
in its capacity. Of course a machine 
which is to run from 1,000 to 1,800 
revolutions per minute without attention 
for long periods must have special pro¬ 
visions for lubrication, and this is gen¬ 
erally attained by “ring oilers” or 
“bucket chains”—devices to carry up and 
pour oil over the bearings constantly 
from an oil well beneath, the oil of 
course being constantly returned by 
gravity and thus used over and over 
again. '1 hen, too, if a dynamo is to 
furnish satisfactory current for electric 
lamps, it is a prime essential that it 
shall run at very nearly uniform speed, 
regardless of the “load.” For example, 
if a generator is rated to run 1,500 revo¬ 
lutions per minute, this should always 
be its speed, whether it is carrying only 
a single lamp or is loaded up to its full 
capacity. Machines are generally pro¬ 
vided with a device known as a 
“rheostat,” which enables one to change 
the voltage of the’ current without 
changing the speed. So we must have 
a water-wheel governor. The simpler 
and cheaper types of governors are 
rather slow in action, requiring as much 
as 60 seconds or even more to effect a 
full gate movement, but may be depend¬ 
ed upon to bring the speed back to the 
correct rate. This slow regulation 
means that we must not throw off too 
many lights with one switch, otherwise 
we shall have excessive voltage for a 
moment. Governors are made which 
claim to give regulation as perfect as 
the best steam engines, but this type is 
too complex and expensive for farmers. 
It should be said that this little plant 
represents rigid economy in planning 
26. and installation. The brook, as has 
been said, is a small one, largely made 
up in a dry time of one large spring, and thus has al¬ 
ways some water, while never very hard to control in 
time of flood. Of course under such circumstances, 
the question of water economy must be looked after. 
The head available is about 15 feet. The wheel is a 
nine-inch upright turbine in a wooden case, and should 
furnish about 4K> horse power. The dynamo is known 
as a 3 K. W. 125 volt machine, which means one that 
at full capacity should take care of about 50 ordinary 
16 candle-power lamps. This higher voltage is needed 
in order to allow for the “drop” in voltage in coming 
the 3,000 feet to the house. Theoretically, a horse 
power should light about 14 lamps, but in practice 
