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least crossing of the streams that run through it: on thecontrary greatest part of the water issued in two oppositedirections, horizontally, from between the ends of theplates.

SECT. II.

’Experiments and observations for the improvement of the fore-going machines, andfor establishing their principles of a£lion.

I. Of the quantity of water they require, and the quantityor force of the air they aford.

H E quantity of water may be estimated with fussi-

1 cient exactness, from the height of the water inthe funnel or bason en the top, and from the width ofthe choak or throat of the funnel, through which it ispressed by the force of a column of that height.

Defaguliers found, by an experiment often repeated,that the quantity of water running through a square inchhole, twenty-five inches under the surface, is five tonsand a fifth in an hour, the ton containing two hundredand sifty-two gallons. The quantities discharged throughequal holes at different depths being as the square rootsof the depths, and the quantities through different holesat equal depths being as the areas of the holes ; it willappear on calculation, that in the machine at Lead-hills,whose funnel is five feet high, and its throat three inchesand a half in diameter, the expence of water is somewhatmore than feventy-feven tons in an hour, or near threehundred and twenty-four gallons in a minute ; and thatin the machine of Dauphiny, where the height of waterin the funnel is only about half as great, and the bore ofthe throat a little wider, the quantity of water is abouttwo hundred and sixty-six gallons in a minute. Perhapsthe real quantity of water mav be somewhat less than this

calculation