502

Raising Water with. Open Tubes.

[Book V.

force required to Work the larger tubes was very sensible, but with thesmaller ones it was scarcely appreciable. Those whose larger ends were2 inches and 1§ inches produced the highest jets, but they were obviouslytoo much tapered for practical purposes, and even the sides of the smallestone named, formed too large an angle to be applied with advantage atgreat depths.

The tube No. 230, two feet one inch in length, was made of tin plate.lt consisted of a conical piece 22 inches long, lj inches wide at one end,and ^ inch at the other. To the wide end a flaring piece, 3 inches longand 4 diametet- at the lower edge, was added. This piece was made ofsheet lead for the convenience of forming it. When wholly immersed inwater, except 2 or 3 inches by which it was held, this tube threw a jet 15feet high. By the upward stroke the jet rose 12 feet. When the diverg-ing ajutage A (whose contracted part was the same as the orifice of thetube) was slipped on the latter, the jet was dispersed before it rose 8 feet.An inch was cut off the lower end, leaving the diameter 3 inches, uponwhich the jet rose to about 14 feet. Another inch was then removed,when it rose still lower; yet it might still, by a quick back stroke, bethrown nearly as high as at the first. It would therefore seem, that al-though a large flaring end requires more force to raise it than a small one,yet the increased velocity required to be given to the downward stroke,in Order to raise the jet to an equal height, comes to much the same thing.There is a way however by which the resistance which a large flaring endmeets with from the water may be avoided in the upward stroke, viz. byenclosing the tube in an air-tight cylindrical one, of the diameter of theflaring end, as represented by the dotted lines in No. 230 : or the instru-ment might be inserted in a wooden tube, whose specific gravity wasabout the same or rather less than that of water.

No. 231 was 3J feet long, formed of copper, and of a regulär taper towithin four inches of its lower end. Its diameter at the small end washalf an inch, and at the lower end 3J inches, to which a piece flared outto six inches was added. By an upward stroke of 18 inches, the jet rose17 feet; and by a downward stroke of one foot, it rose to the same height.(These measurements, and the others mentioned, relate to the extremeheight to which a small part only of the liquid rose. The main body ofthe jet seldom reached over two-thirds of the distance.) When the up^ward stroke was continued 2J feet, the rushing air pushed all the waterout of the tube, and rose up on the Outside.

Exper. VIII.—We next prepared a larger tube, and arranged it so asto be worked in a light wooden frame, which was secured in a wine pipefilled with water. (See No. 233. The wine cask is omitted.) This In-strument was deemed equal to any that was tried—the quantity of water,and the elevation to which it was raised, being compared with the forceemployed. It should not, however, be considered as exhibiting anythinglike the maximum effect which spouting tubes are capable of producing,because the friction of the liquid in passing through so small an orifice asthat of No. 233 was very considerable. The reader is therefore requestedto bear in mind, that the larger the bore of these tubes, the more favorablewould be the result; and that, although jets of water may be thrown veryhigh by them, yet they are better adapted to raise large volumes of waterto small heights.

The tube No. 233 was five feet long. It was composed of one piece 4feet 4 inches in length, .75 of an inch diameter at one end, and 2.9 inchesat the other. To this end a piece 5 inches long was added, which madethe diameter 5.5 inches; and to this another piece 3 inches long, which