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air occupying part of the cavity of the pipe; and thatthis air passes down on the outside of the water, orin a separate column, not intermixed with it so as to ren-der it frothy.

Water descending through an oblique pipe with lateral

apertures.

I varied the foregoing experiment by taking, insteadof the crane, a leaden pipe, about ten feet lortg and threequarters of an inch bore. Several holes were made, atintervals, in the length of the pipe, and small tubes fixedinto them like the sucking pipe of the crane. The pipebeing laid aslope, its upper end was turned up perpendi-cularly, and a funnel fitted to it, which was supplied withwater by a cock in the bottom of a reservoir : the otherend of the pipe, which the water issued from, was insertedinto the air vessel used in the preceding experiment.

The lateral tubes being stopt, and the cock so turnedas to let the water run fast enough to keep the funnelalways full, no air issued from the blowing pipe. Onopening the tubes, a considerable blast was perceived;the water passed flower through the pipe, so that the samestream made the funnel run over; and on pulling outsome of the tubes, and looking in through the holes, thecolumn of water was very visibly less than the bore of thepipe. The tubes being stopt again, the blast ceased, andthe stream did no more than keep the funnel full.

A small variation in the circumstances of this experi-ment made a very material difference in the effect. Thesupply of water having been diminished, so as to rife onlya little way above the throat of the funnel, a prettystrong blast issued from the blowing pipe though all thelateral tubes were closely stopt; and when the tubes wereopen, instead of air ’pasting in by them, a blast passed

out