Page:Lowell Hydraulic Experiments, 4th edition.djvu/82

waste of water; it is possible that some such effect may be produced by them. The author is not aware that any exact experiments have been made on the power of these wheels; from their form and construction, however, it is plain that they cannot be classed among those using water with very great economy. In the design for the Boott wheel, the author has so modified the form and arrangement of the whole, as to produce a wheel essentially different from the Howd wheel, as above described, although it may, possibly, be technically covered by the patent for that wheel.

112. Figures 1 and 2, plate VIII, are a vertical section, and a plan of the Boott centre-vent wheel, showing, also, the apparatus used in the experiments. $A$, the lower end of a pipe, about one hundred and thirty fret long, and eight feet in diameter, by which the water is conducted into the forebay $B$; this pipe is constructed of plate iron, three eighths of an inch in thickness, riveted together in the usual manner of making steam-boilers. For local reasons, the top of the forebay $B$ is closed, so as to prevent the water from rising to its natural level, by about six or seven feet. $C$, the surface of the water in the Merrimack River, represented at about its medium height during the experiments. $D$, the wheel;$E$, the guides; $F$, the regulating gate, the apparatus for moving which, is not represented; $G$, the disc, which relieves the wheel from the vertical pressure of the water, and which also supports the lower bearing of the vertical shaft. The leather packing of the regulating gate $F$, slides against the circumference of the disc, which is turned smooth and cylindrical for that purpose, and the disc itself is supported by means of four brackets, two of which are represented at $HH$, by the columns $II$ The vertical shaft $K$ is of wrought iron, and it passes through the stuffing box $L$, and is supported by the box $M$, which has a series of recesses lined with babbit metal, fitted to receive a corresponding series of projections in the vertical shaft. The wheel, the vertical shaft, and the bevel gear usually on the latter, have a total weight of about 15,200 pounds; the bearing surface in the box $M$ is about 331 square inches, consequently, the weight, per square inch, of bearing surface, is about 46 pounds.

Figures 3 and 4, plate VIII, represent the wheel and guides on a larger scale. The buckets and guides are equal in number, there being forty of each; the buckets are of plate iron, 1/4 of an inch in thickness; the guides are of the same material, 3/16 of an inch in thickness. The following dimensions were taken after the parts were finished: —

Mean shortest distance between adjacent buckets, or ${\textstyle ab}$ figure 4, .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .     .

0.1384 feet.