SYNOPTICAL TABLES.
359
| Probable average distance of stars of 6th magnitude, | 120 |
| Nebulæ, proportion of sphere containing one-third of whole mass, near north pole of the galaxy, | 1-8th |
| Largest proper motion, 1830, Groombridge, | 7″ |
| Diameter of the Sun removed to a distance corresponding to one-second parallax, | 0″.0093 |
| Light of Sirius (Sun's = 1 at the same distance), | 63 |
| Light of the Sun (Sirius = 1) at the Earth, | 20,000,000,000 |
| Variable star Algole, period, | 2d 20h 48m |
| Variable star Algole, variation in magnitude, | 2.4 |
| Variable star δ Cephei, period, | 5d 8h 47m |
| Variable star δ Cephei, variation in magnitude, | 3.5 |
| Variable star β Lyræ., period, | 12d 23h 53m |
| Variable star, β Lyræ. variation in magnitude, | 3.4 |
| Number of variable stars, with assigned periods, about | 6O |
| Double stars, odds against one chance combination of 4″ closeness, | 9570 to 1 |
| Double stars, number of such combinations, upwards of | 100 |
| Sun's distance from Alcyone, the centre of the stellar system (Mædlar), (radius of Earth's orbit = 1), | 34,000,000 |
| Sun's time of revolution round Alcyone, in years, | 19,256,000 |
| Sun's velocity in space (Earth's annual motion = 1), | 1.4 |
| Sun, point in Hercules, to which it is moving, | |
| Sun, point in Hercules, north declination, | 34° 37′ |
| Sun, point in Hercules, right ascension, | 259°'90 |
| Lord Rosse's Great Reflector, diameter of mirror, in feet, | 6 |
| Lord Rosse's Great Reflector, thickness of mirror, in inches, | 5 |
