499

Chap. 4.] Experiments with Spouting ör Open Tubes.

feet, and sixteen inches dip caused it to ascend over seven feet. The risein cylindrical tubes, we have seen, bore the same relation to the dip atvarious deptbs ; but this experiment shows that the elevation of the jet inconical tubes increases in a much greater ratio.

Exper. IV.—To include the extreme proportions between the two ori-fices, we next took a matrass or bolt head (No. 225) and cut a portionfrom the globe opposite the junction of the neck or pipe. The openingthus made was 3J inches, and the orifice of the tube three-tenths. Whenthe lower end was thrust two inches below the surface, scarcely any risetook place upon removing the finger; and when half the length of thewhole was immersed, say ten inches, the rise did not exceed six or seven.The reason was plain : the large volume of air eontained in the lower partcould not be expelled instantaneously by the pressure of the liquid columnthrough the small orifice above, but the force of the ascending liquid wasconsumed in doing this. Various portions were now cut from the lowerpart, with a view to ascertain the greatest rise that could be obtained witha dip of four inches. This occurred when the diameter of the lower endwas reduced to 1§ inches : the liquid then rose between nine and teninches above the surface. The upper end was now heated in the flameof a lamp, and the bore enlarged by pressing into it a tapered piece ofwood, tili the end resembled the conical ajutage C D in No. 201. Thiscaused the liquid to rise an inch higher.

Exper. V.—A number of conical tubes of the same length, (21 inches)whose wide ends diverged or flared differently, were next procured, withthe view of selecting those through whic.h the jet rose the highest, asaffording an approximation to the best form. The one represented atNo.226 gave a better result than any other. With a dip of four inches thejet rose thirteen. The diameter of its lower orifice was 1.6 inches,. andthat of the upper one .4: three inches below the latter, the bore was . 2 .At seven inches from the small end, the bore was .3-—at f’ourteen inches,.4—and at seventeen inches, .5. The curve given to the fiaring part ofthe lower end should be that which the fluid itself assumes in entering;but that given in the figure is sufBcient for all praetical purposes to whichsmall instruments of this kind are applicable.

Before proceeding we may observe, that these instruments, simple asthey are, and even when charged in the manner indicated above, are sus-ceptible of some useful applications ; among which may be named siphons.If the tube No. 226 were bent in the form of one, it might be applied innumerous cases to transfer acids or other liquids ; and as it would becharged by the mere act of inserting its short leg into the liquid to bewithdrawn, there could be no danger from sueking, &c. as in using theordinary instrument. It will moreover be perceived from the third expe-riment, that the extent to which these siphons are applicable increaseswith the depth to which the short leg can be immersed : but as this chapteris appropriated to the application of spouting tubes to raise water fromone level and discharge it at a higher one, their employment as siphonswill be illustrated in a subsequent part of this volume.

It will at once occur to every machinist, that to render these tubes ofany praetical value for raising water, some mode of working them verydifferent from that of alternately opening and closing the upper orifice withthe finger, and raising them wholly out of and then plunging them into theliquid, would be required : a mode of regularly and rapidly depressingthe liquid within them, that the wave formed by its ascent might rise andfall uniformly.

There is a simple way of doing this :—If the whole of the tube No. 227