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By trying several of these funnels, we came to certainsizes, which could not be much increased or diminished,without diminishing the effect of the machine ; but is thereis, in this respect, any exact standard, our experiments didnot discover it. There are so many circumstances, as wehave already seen, which influence the effect, that it is verydifficult to judge, when the differences are small, how farthey depend on any particular one. When the area of theorifice of the pipe was from four to five times greater thanthat of the funnel, the differences in the height of thegage were not -very considerable : the due proportions seemto lie within these bounds, and perhaps nearer to the latterthan to the former; for when the funnel was only about asixth part of the area of the pipe, the gage stood ratherhigher than when it was a third part, from whence theproportions should be as one to somewhat more than fourand a half.

Experiments of dividing the Jiream so as to increase its effeSi,and render less water sufficient.

As the effect of these kinds of machines depends onthe water being spread and divided, and the air, whichcomes in to fill the interstices between the little streamsor drops which compose the jet, being pushed down withvelocity by the succeeding water ; I have endeavoured todivide the stream, more effectually than is done in thecommon machines, and with little or no diminution ofits velocity, by varying the form of the aperture of thefunnel.

On the orifice of the funnel I fitted a perforated tin plate,like the nose of a watering pot, but with the holes larger,and of a triangular figure ; this figure was chosen on ac-count of its great surface, water, passing through a triangu-lar aperture, having about a third part more surface than

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