QQP Gravity and Levity

From Cambridge University Library Add. MS 3996, Questiones Quædam Philosophicæ (Certain Philosophical Questions, now published by McGuire and Tamny.) Square brackets, [ ], are my comments and [ . . . . . . . ] indicates an omitted section. There is also a discussion of the Two Falling Globes section.

Of Gravity & Levity

The matter causing gravity must pass through all y^e pores of a body. it must ascend againe. 1 for else y^e bowells of y^e earth must have had large cavitys & inantys to conteine it in 2 or else y^e matter must swell it. 3 y^e matter y^t hath so forcibly borne dow y^e earth & all other bodys to y^e center (unles you will have it growne to as gross a consistence as y^e Earth is, & hardly yⁿ) cannot if added to gether be of a bulke so little as y^e Earth, For it must descend exceding fast & swift as appeares by y^e falling of bodys, & exceeding weighty pressure to y^e Earth. It must ascend in another forme yⁿ it descendeth or else it would have a like force to beare bodys up y^t it hath to press y^m downe & so there would bee no gravity. It must ascend in a grosser consistence yⁿ it descends 1 because it may be slower & not strike boddys w^th so greate a force to impell y^m upward 2 y^t [this sentence continued on 67 121^r ]

Gravity & levity

anothers streames w^th much difficulty, & pressure & so be compacted & y^e descending streame will keepe y^m so by continually pressing y^m to y^e Earth till they arise to y^e place from whence they came, & there they will attaine theire former liberty.

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The weight of water is to y^e weight of quicsilver as 1 is to 14. Water is 400 (perhaps 2000) times heavier yⁿ aire & gold 19 times heavier yⁿ water.

Quæst: What proportion y^e weights of two bodys as gold & silver have have in divers mediums as in vacuo aere aqua &c: w^ch known y^e weight of y^e aire or water in vacuo or the quantity of gold to y^e silver is given &c

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Try whither flame will descend in Torricellius vacuu.

68 121^v

In y^e descention of a body There is to be considered y^e force w^ch it receives every moment from its gravity (w^ch must bee least in a swiftest body) & y^e opposition it receives from y^e aire (w^ch increaseth in pportion to its switfnesse). To make an experiment concerning this increase of motion When y^e Globe a is falne from e to f let y^e Globe b begin to move at g soe y^t both y^e globes fall together at h.

According to Galilæus a iron ball of 100^l Florentine (y^t is 78^l at London of Adverdupois weight) descends an 100 braces Florentine or cubits (or 49,01 Ells, perhaps 66^yds) in 5'' of an hower.

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Try whither y^e weight of a body may be altered by heate or cold, by dilatation or condensition, beating, poudering, transfering to severall places or sev^rall heights or placing a hot or heavy body over it, or under it, or by magnetisme. whither leade or its dust spread abroade, whither a plate flat ways or edg ways is heaviest. Whither y^e rays of gravity may bee stopped by reflecting or refracting y^m

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The gravity of bodys is as their solidity, because all bodys descend equall spaces in equall times consideration being had to the Resistance of y^e aire &c.