30OK HI.] OF NATURAL PHILOSOPHY. 453 about three times less than the accelerative gravity on the surface of thr earth. COR. 6. And the distance of the moon's centre from the centre of the earth will be to the distance of the moon's centre from the common centre of gravity of the earth and moon as 40,783 to 39,788. COR. 7. And the mean distance of the centre of the moon from the centre of the earth will be (in the moon's octants) nearly 60f of the great est semi-diameters of the earth; for the greatest semi- diameter of the earth was 1 9658600 Paris feet, and the mean distance of the centres of the earth and moon, consisting of 60