In the article on page 208—on the power of falling water—it was stated that the power which propels machinery is estimated by multiplying the weight into the velocity of the moving body such as the weight of the water into its speed. Examples showing how the amount of power was calculated were also presented. The object of this article is to point out the means of estimating the amount of water which will pass through a certain opening of sluice or through a certain open space in a given amount of time. The quantity of water which flows in a stream in a given time is generally ascer tained by
In the article on page 208—on the power of falling water—it was stated that the power which propels machinery is estimated by multiplying the weight into the velocity of the moving body such as the weight of the water into its speed. Examples showing how the amount of power was calculated were also presented. The object of this article is to point out the means of estimating the amount of water which will pass through a certain opening of sluice or through a certain open space in a given amount of time. The quantity of water which flows in a stream in a given time is generally ascer tained by the open area of a sluice or else by a rectangular notch cut in a board in the edge of the dam at the surface of the water ; so that the section of the passing stream may be measured as it flows through the notch. If water flows through an opening regulated by a sluice in the flume of a dam and the dis charge is constant—the dam maintaining a uniform level above the opening—how can the quantity of water which flows through the opening of the sluice be ascertained ? If the laws of gravitation (without correction) governed the flow it would only be necessary to measure the area of the opening and calculate the velocity as that of a body falling from the surface of a dam through the centre of the orifice and the area multi plied by that velocity would give the quantity of water passing through it in a certain time. In the same manner if no correction were required to find the quantity flowing through a rectangular notch in the plank or weir on the edge of the dam it would oulybe requisite to measure the bight from the surface of the dam to the bottom of the notch in order to find the velocity of the water as by the law of falling bodies and then take two-thirds of the quantity which would flow at that veloci ty through the area of the notch for the area of the p trabola described by the notch—it being two-thirds of its circumscribed rectan gle. Such were the rules given
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