. Development and electrical distribution of water power . e stream. With a steeltape, weighted at one end by a heavy plumb bob, measure thedepth of the water at each marking on the transversely stretchedwire, using a small row-boat when necessary. From these datathe cross-section may be mapped and computed. This is done by assuming some scale on the paper, say -^ °fan inch, as equal to one foot of horizontal distance, and some othergreater scale, say one inch, as equal to one foot of vertical measure-ment. Computing the area of the cross-section of the water may GENERAL CONDITIONS J be done b
. Development and electrical distribution of water power . e stream. With a steeltape, weighted at one end by a heavy plumb bob, measure thedepth of the water at each marking on the transversely stretchedwire, using a small row-boat when necessary. From these datathe cross-section may be mapped and computed. This is done by assuming some scale on the paper, say -^ °fan inch, as equal to one foot of horizontal distance, and some othergreater scale, say one inch, as equal to one foot of vertical measure-ment. Computing the area of the cross-section of the water may GENERAL CONDITIONS J be done by any method of integrating irregular surfaces. A simpleapproximate way is to add together all the observed depths anddivide this result by the number of observations. This givesthe average depth. Multiply this average depth by the width ofthe stream, in feet, and the product will equal the cross-sectionof the stream in square feet. The float should be made of a piece of wood about three feetlong and from six to ten inches in diameter. Weights should be. Fig. i. fastened to one end of the piece so that it will float vertically,with one end submerged and the other projecting only an inchor two above the surface of the water. In order to observe from the bank the position of the float, 8 DEVELOPMENT AND DISTRIBUTION OF WATER POWER it is usual to fasten a small piece of red cloth to a rod or pieceof wire and drive this rod into the upper end of the float. The distance apart of the two points selected to observe thefloat velocity should be accurately measured and stakes drivenin the ground near the waters edge, to fix these reference points. The foregoing instructions are for determining the flow ofmoderate and large-sized streams. In measuring small streams it is more accurate and convenientto construct a weir dam such as is shown in Fig. i. This is madeof boards as is indicated, with a notch B extending across abouttwo-thirds the width of the stream and deep enough to easily pas
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