that drove the bullet: I did therefore take notice that in this occasion the Air bear’s a pressure much about the same as that of water when it’s spring is 32 foot high: now such water would spout out with a sufficient velocity to ascend 32 foot perpendicular: and therefore, according to the rules and observations of <u>Galileus <\u> Mr Halley etc, such water hath the velocity of 44 foot in a second. It remains therefore but to know the proportion of the gravity of <s>the <\s> Air to that of water: and we have found it to be always not the same: because the heigth, the heat, and the moisture of the Atmosphaere are variable: nevertheless we may say in general that the reason between the specifick gravitys of Water and Air is much about 840. [text?] taking then their square root’s, as I have say’d above, which root’s are 29. and 1. we may conclude that the velocity of Air must exceed that of water by 29 times: and so multiplying 44 velocity of water by 29 we <s>will <\s> shall find that the Velocity of Air driven by the whole pressure of the Atmosphaere is about 1364 foot in a second.
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Of the Velocity of Air passing into an Exhausted receiver by Denis Papin, 1686. From The Royal Society, CLP/18i/35
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