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Experiments with Spouting or Open Tubes. [Book V.

the liquid will rise within it the moment its end is opened; but it willdepend upon the length and figure of the tube, and the relative proportionof its two orifices, whether the liquid rush up above the surface without,or slowly reach it and there remain.

The following are selected from a number of experiments made severalyears ago. Instead of closing the lower orifice, the upper one was closedwith the fore finger, the confined air acting the part of a cork, and pre-venting the liquid from entering until the finger was removed.

Nos. 222. 223. 224. 225.

Exper. I. —No. 222, a cylindrical glass tube, 18 inches long and half inchbore. Its upper orifice was closed air-tight, by the finger, and the lowerone then held four inches under the surface of the water in the vessel.Upon raising the finger, the liquid rose in the tube six inches; i. e. itsmomentum carried it two inches higher than the surface in the cistern,and after a few oscillations it settled at the same level. Cylindricaltubes of various sizes were tried at different depths, and the average ex-tent of the rise (above the surface) was equal to half the length of the partof the tube immersed below the surface. If No. 222 dipped four inches,the rise was two—if eight inches, it was four—and if twelve, it was six.By contracting either orifice the effect was diminished.

Exper. II.—No. 223, a tube slightly conical, 16 inches long, the dia-meter or bore of the large end half an inch, and that of the small end one-third of an inch. The rise of the liquid in this exceeded that in No. 222.When tried with the large end up, little or no rise took place.

Exper. III.—No. 224, another tube, 18 inches in length, the diameterof whose upper orifice was three-sixteenths and of the lower seven-eighthsof an inch. Four and a half inches of the lower part was cylindrical.When dipped four inches in water and the finger removed, the liquid rosebut two inches above the surface. This was owing to the cylindrical formof the lower part of the tube, all the water that entered being required tofill the lower part. When the dip was six inches, the rise was five; wheneight, the jet passed out of the tube and ascended sixteen inches. Whenthe tube was lowered to ten inches below the surface, the jet rose thirtyinches; and when the end of the tube was twelve inches under the surface,the jet ascended four feet and a half. Fourteen inches dip threw it six