Finally, as to the added value a water-power electric plant adds to the selling price of a farm. Let the farmer answer this question for himself. If he can advertise his farm for sale, with a paragraph running: "Hydroelectric plant on the premises, furnishing electricity for light, heat, and power"--what do you suppose a wide-awake purchaser would be willing to pay for that? Perkins and his neighbor believe that $1,000 is a very modest estimate added by their electric plant to both places. And they talk of doing still more. They use only a quarter of the power of the water that is running to waste through the wheel. They are figuring on installing a larger dynamo, of say 30 electrical horse-power, which will provide clean, dry, safe heat for their houses even on the coldest days in winter. When they have done this, they will consider that they are really putting their small river to work. CHAPTER II A LITTLE PROSPECTING Small amount of water required for an electric plant--Exploring, on a dull day--A rough and ready weir--What a little water will do--The water wheel and the dynamo--Electricity consumed the instant it is produced--The price of the average small plant, not counting labor. The average farmer makes the mistake of considering that one must have a river of some size to develop power of any practical use. On your next free day do a little prospecting. We have already said that 250 cubic feet of water falling 10 feet a minute will provide light, heat and small motor power for the average farm. A single water horsepower will generate enough electricity to provide light for the house and barn. But let us take five horsepower as a desirable minimum in this instance. [Illustration: Measuring a small stream with a weir] In your neighborhood there is a creek three or four feet wide, toiling along day by day, at its task of watering your fields. Find a wide board a little longer than the width of this creek you have scorned. Set it upright across the stream between the banks, so that no water flows around the ends or under it. It should be high enough to set the water back to a dead level for a few feet upstream, before it overflows. Cut a gate in this board, say three feet wide and ten inches deep, or according to the size of a stream. Cut this gate from the top, so that all the water of the stream will flow through the opening, and still maintain a level for several feet back of the board.