. Appleton's dictionary of machines, mechanics, engine-work, and engineering. 17have 17 = 13-6 inches, which does not differ greatly from M. Eytelweins rule, in which we have most confidence, from our own experience, when the volume of water is very great. For smaller quan-tities of water, such as we find in leads cut to supply bucketed wheels, the modification which we havegiven of De Pronys rule is much more convenient, and we have found it, in general, very correct. It is frequently difficult, and sometimes impossible, to apply any of these rules to determine thevolume of water furnished; a
. Appleton's dictionary of machines, mechanics, engine-work, and engineering. 17have 17 = 13-6 inches, which does not differ greatly from M. Eytelweins rule, in which we have most confidence, from our own experience, when the volume of water is very great. For smaller quan-tities of water, such as we find in leads cut to supply bucketed wheels, the modification which we havegiven of De Pronys rule is much more convenient, and we have found it, in general, very correct. It is frequently difficult, and sometimes impossible, to apply any of these rules to determine thevolume of water furnished; and it is often of importance, as when considerable accuracy is desired, toresort to more than one mode of measurement. In all ordinary experiments of this kind, there is acertain degree of uncertainty arising from inaccuracy of measurement; it is therefore of importance tohave the means of checking the result of one rule by that obtained by a different process. The follow-ing method, which is not only simple and generally applicable, but likewise admitting of considerable. accuracy, will therefore be useful. This consists in erecting a notch in some convenient part of thewatercourse where the velocity is not great. The notch is easily formed in leads of moderate size byaboard A A, Fig. 3806, stretched across the channel, and having a rectangular part AcdA cut ornotched out in the manner shown in Fig. 3807, and through which the whole of the water will be made WATER-WHEELS. 863 to pass. The notch-board being fixed, a rod B must be fixed vertically in the channel a few yards be-hind, and having a mark n upon it at exactly the level of the edge c d of the notch. The water beingthen permitted to descend in the lead, let its depth n in upon the rod B be carefully noted in inches,then taking from the second or third column of the annexed table the quantity corresponding to oneinch of width at the depth noted, multiply that quantity by the whole width in inches, and the resultwill be
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Keywords: ., bookcentury1800, booksubjectmechanicalengineering, bookyear1861
