EXTRUDED BY PRESSURE. <£-j t 



Pa per. I. The altitude of T above the veflel is 30 inches. Experiment I. 

 Time of expelling the air, by feveral trials, is 33 feconds. £««£ a &U of 33 



Exper. II. The altitude of T is fix feet. The time of filling, Experiment II* 

 by feveral trials, is 21 .3 feconds* wit h a fail of 7* 



In the firft experiment, 425.088, the folidity of the vefifeI >' Compl'tation of 



divided by .004-6, the area of the hole a, gives 92410.4- inches the firft experi- 



for the length of the dream of air driven out in 33 feconds ; me f 8»™ ac- 



o tual velocity per 



divide that length by 33, and we (hall have 233.3 feet, the ve-f ec . = z ^ 



locityper fecond, communicated by 30 inches of water. f eet J 



The fecond experiment by the fame procefs gives 361.6 feet am j f the ( tcm M 

 per fecond. If we would compare thefe together, we mayg» ve s 361.6 per 

 fay, as the fquare root of 30, the head, is to 233.3, the velo- 

 city ; fo is the fquare root of 72, the fecond head, to 361.8 

 feet, the velocity per fecond. 



Again : — As the fquare root of 6 feet is to 361*6, fo is <-he Whence h 

 fquare root of 33 feet to 845.2 feet per fecond, the velocity locity of air fro in 

 produced by that head, or the initial velocity with which thef he atmof phere 



J J . '"to a vacuum i$ 



atmofphere would enter a vacuum. This velocity, found by computed, and 

 experiment, is 487 het per fecond lefs than has been affigned * urns out t0 De 



. \T b 845.2 inftead of 



by theory. 133* feet, as by 



It appears however that the refults, as determined by the- theory, 

 ory and experiment, do not differ more than in the cafe of efflu- correc^ed 1 !^ the 

 ent water. For, if we would reduce the velocity of effluent multiplier given 

 water found by theory, to that which experience gives, we^gjj*" 16 " 06 

 muft multiply it by .634. Accordingly, if we multiply 1332 ter, proves to be 

 feet } the velocity of the atmofphere entering a vacuum as cal- ver ^ corre &« 

 culated above, by .634, the product is 844.5 per fecond, differ- 

 ing but T 7 ^ of a foot from that juft found by experiment. 



I have alfo made experiments by finking veffels in water, till Experiments 

 their tops were even with its furface, and opening the aperture Wltn rilin S wa * 

 that the rifing water might expel the air, by which I obtained 

 the fame velocities as above; but the method of computing is 

 much more intricate, for which reafon I lliallnot infer t them. 



From the above it appears, that a preffure equal to 33 feet General refults 

 of water, will expel air out of the bellows into the atmofphere 

 with a velocity of 845 teet per fecond ; that one foot of water 

 in depth will produce a velocity of 147 J feet, and one inch a 

 velocity of 42 feet per fecond, or 20 miles an hour. 



Hence we may conftruct a table fhewing the velocity com- applied to the 

 municated to air by any head of watery for as the fquare root conftru<ftion of 



* .tables for effl u- 



°J ent air prelTed by 

 water j 



