Of the Attraction ^Gravitation.

Hence we learn that all Bodies haveWeight, or are heavy ; and that there isno such Thing as absolute Levity in Na-ture; and by the second Law, the Weightof all Bodies is proportional to the Quan-tity of Matter they contain; and hence,since Bodies of equal Bulks are found tohave unequal Quantities of Matter, it e-vidently follows, that a Vacuum, orSpace void of Matter, must necessarilyexist, and that an absolute Plenum is a

stances ; but with their joint Forces, in vast Quanti-ties, produce a mighty Power, whose Efficacy extendsto very great Distances, proportional to the Magnitudeof Bodies.

2. This Force of Gravity is, to Sense, the same forany Distances near the Earth’s Surface; since a smallDistance from the Surface of the Earth does not sen-sibly alter the Distance from the Centre, which is near4000 Miles : At the Height therefore of one Mile; for In-stance, the Distances from the Centre will be as theNumbers 4000 to 4001, and the Powers of Gravity in-versely as their Squares, viz. 16008001 to 16000000,or as 16008 to 16000, which are so near an Equalityas not to be sensibly different from each other.

3. But when the Distance is so great as to cause aDisproportion between that and the Semidiameter of theEarth, then will the Power of Gravity decrease verysensibly, according to the Law above laid down : Thusat the Distance of the Moon, which is, at a Mean,about 60 Scmidiameters of the Earth, the Power ofGravity is to that on the Earth’s Surface as 1 to 3600,as will be strewn under the Article of Central Forces withsufficient Demonstration.

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Doctrine