The Ptolemean System absurd.
96. In the Ptolemean System the Earth was supposed to be fixed in the Center of the Universe; and that the Moon, Mercury, Venus, the Sun, Mars, Jupiter, and Saturn moved round the Earth: above the Planets, this Hypothesis placed the Firmament of Stars, and then the two Crystalline Spheres; all which were included in and received motion from the Primum Mobile, which constantly revolved about the Earth in 24 hours, from East to West. But as this rude Scheme was found incapable to stand the test of art and observation, it was soon rejected by all true philosophers; notwithstanding the opposition and violence of blind and zealous bigots.
The Tychonic System, partly true and partly false.
97. The Tychonic System succeeded the Ptolemean, but was never so generally received. In this the Earth was supposed to stand still in the Center of the Universe or Firmament of Stars, and the Sun to revolve about it every 24 hours; the Planets, Mercury, Venus, Mars, Jupiter, and Saturn, going round the Sun in the times already mentioned. But some of Tycho’s disciples supposed the Earth to have a diurnal motion round it’s Axis, and the Sun with all the above Planets to go round the Earth in a year; the Planets moving round the Sun in the foresaid times. This hypothesis, being partly true and partly false, was embraced by few; and soon gave way to the only true and rational System, restored by Copernicus and demonstrated by Sir Isaac Newton.
98. To bring the foregoing particulars at once in view, with several others which follow, concerning the Periods, Distances, Bulks, &c. of the Planets, the following Table is inserted.
A TABLE
Of the PERIODS, REVOLUTIONS, MAGNITUDES, &c. of the PLANETS.
| Sun and Planets. | Annual period round the Sun. | Diurnal rotation on it’s Axis. | Diameter in English miles. | Mean diam. as seen fr. the Sun. | Mean distance from the Sun in English miles. |
|---|---|---|---|---|---|
| Sun | ---- | 25d. 6h. | 763000 | ---- | ---- |
| Mercury | 87d 23h | Unknown. | 2600 | 20ʺ | 32,000,000 |
| Venus | 224d 17h | 24d. 8h. | 7906 | 30ʺ | 59,000,000 |
| Earth | 365d 6h | 1d. 0h. | 7970 | 21ʺ | 81,000,000 |
| Moon | 365d 6h | 29d. 123⁄4h. | 2180 | 6ʺ | 81,000,000 |
| Mars | 686d 23h | 24h. 40m. | 4444 | 11ʺ | 123,000,000 |
| Jupiter | 4332d 12h | 9h. 56m. | 81000 | 37ʺ | 424,000,000 |
| Saturn | 10759d 7h | Unknown. | 67000 | 16ʺ | 777,000,000 |
| Sun and Planets. | Excentricity of it’s Orbit in miles. | Axis inclined to Orbit. | Orbit inclined to Ecliptic. | Place of it’s Aphelion. | Place of it’s Ascending Node. | Proportion of Diameters. |
|---|---|---|---|---|---|---|
| Sun | ---- | 8° 0ʹ | ---- | ---- | ---- | 10000 |
| Mercury | 6,720,000 | Unkn. | 6° 54ʹ | ♐ 13° 8ʹ | ♉ 14° 43ʹ | 341⁄10 |
| Venus | 413,000 | 75° 0ʹ | 3° 20ʹ | ♒ 4° 20ʹ | ♊ 13° 59ʹ | 1031⁄2 |
| Earth | 1,377,000 | 23° 29ʹ | 0° 0ʹ | ♑ 8° 1ʹ | ---- | 1041⁄2 |
| Moon | 13,000 | 2° 10ʹ | 5° 8ʹ | ---- | Variable. | 281⁄2 |
| Mars | 11,439,000 | 0° 0ʹ | 1° 52ʹ | ♍ 0° 32ʹ | ♉ 17° 17ʹ | 581⁄6 |
| Jupiter | 20,352,000 | 0° 0ʹ | 1° 20ʹ | ♎ 9° 10ʹ | ♋ 7° 29ʹ | 10612⁄3 |
| Saturn | 42,735,000 | Unkn. | 2° 30ʹ | ♐ 27° 50ʹ | ♋ 21° 13ʹ | 8781⁄9 |
| Sun and Planets. | Proportion of Bulk. | Prop. of Gravity on the surface. | Proportion of Density. | Proportion of Light & Heat. | Propor. quantity of Matter. | Hourly motion in it’s Orbit. | Hourly motion of it’s Equator. |
|---|---|---|---|---|---|---|---|
| Sun | 877650 | 24 | 251⁄2 | 45000 | 227500 | ---- | 3818 |
| Mercury | 1⁄27 | Unkn. | Unkn. | 61⁄2 | Unkn. | 95000 | Unkn. |
| Venus | 1 | Unkn. | Unkn. | 13⁄4 | Unkn. | 69000 | 43 |
| Earth | 1 | 1 | 100 | 1 | 1 | 58000 | 1042 |
| Moon | 1⁄50 | 34⁄100 | 1231⁄2 | 1 ± | 1⁄40 | 2290 | 91⁄2 |
| Mars | 1⁄5 | Unkn. | Unkn. | 3⁄7 | Unkn. | 47000 | 556 |
| Jupiter | 1049 | 2 | 19 | 1⁄28 | 220 | 25000 | 25920 |
| Saturn | 586 | 11⁄2 | 15 | 1⁄90 | 94 | 18000 | Unkn. |