Astronomy explained upon Sir Isaac Newton's Principles; and made easy to those who have not studied mathematics to which are added, a plain method of ... transit of Venus over the sun's disc, in t - Softcover

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1809 Excerpt: ... by the above reasoning, that while the Earth by its gravity falls toward the Moon, the water directly below her at-4? will swell and rise gradually toward her: also the water at D will recede from the centre (strictly speaking, the centre recedes from DJt and rise on the opposite side of the Earth: while the water at B and F is depressed, and falls below the former level. Hence, as the Earth turns round its axis from the Moon to the Moon again, in 24j hours, there will be two tides of flood and two of ebb in that time, as we find by experience. o 298. As this explanation of the ebbing and flowing of the sea, is deduced from the Earth's constantly falling toward the Moon by the power of gravity, some may find a difficulty in conceiving how this is possible, when the Moon is full, or in opposition to the Sun; since the Earth revolves about the Sun, and must continually fall toward it, and therefore cannot fall contrary ways at the same time: or, if the Earth be constantly falling toward the Moon, they must come together at last. To remove this difficulty, let it be considered, that it is not the centre of the Earth that describes the annual orbit round the Sun, but the common centre of gravity of the Earth and Moon together: and that while the Earth is moving round the Sun, it also describes a circle round that centre of gravity; going as many times round it in one revolution about the Sun as there are lunations or courses of the Moon round the Earth in a year: and therefore, the Earth is constantly falling toward the Moon from a tangent to the circle it describes round the said common centre of gravity. Let M be the Moon, T W part of This centre is as much nearer the Earth's centre than the Moon's, as the Earth is heavier, or contains a greater quantity of ...

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