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The quantity of air introduced appears to depend uponthe degree of this enlargement, and on the quantity ofwater that runs through in a given time.

The greater the height of water above the narrowthroat, the greater velocity will the jet receive, and themore it will be disposed to spread and be enlarged. Thelength of the pipe does not appear to be of so much im-portance : it should seem sufficient if the pipe is of suchlength, that the pressure of water in it may be able toresist the compressed air in the air vessel, and that afterpart of its power has been spent in overcoming that force,it may still have velocity enough left to run down as fastas it can be supplied from the funnel. In order to attainto some determinate proportions, the following trials weremade.

A leaden pipe, seven feet high, and an inch and a halfin diameter, being fitted into an air vessel, as in the fore-going experiments, funnel-shaped pipes of different heightswere supported over it, so as that the small end of thefunnel might hang freely in the orifice of the leaden pipe,and leave space enough for the entrance of air all round.For the greater security os the throat being of the same areain all the funnels, one and the fame copper pipe served asa throat for them all: the funnels being formed by insert-ing this pipe into larger tapering ones of different heights.The funnels were always kept full, and the water conveyedinto them as gently as possible, so as to produce no stalk-ing or twirling motion.

A funnel of one foot high hast very little effect: therising of the gage in the air vessel was inconsiderable,and the stream of air from the blowing pipe was but justto be felt: on opening some holes made in the uprightleaden pipe under the throat of the funnel, the jet of waterappeared not spread, but rather contracted, and did not fill

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