334
SYNOPTICAL TABLES.
| Volume (Earth's = 1), | 1,415,225 |
| Mass (Earth's = 1), | 354,936 |
| Density (Earth's = 1), | 0.2543 |
| Diameter (Earth's = 1), | 111.454 |
| Diameter in miles, | 882,646 |
| Diameterapparent, mean, | 32′ 12″.6 |
| Gravity at equator (Earth's = 1), | 28 |
| In one second of time bodies fall, in feet, | 335 |
| Period of rotation in days, | 25.5 |
| Zone of maximum spots north from the equator, | 11°—15° |
| Usual limit of spots from the equator, | 33° |
| Period of maximum number of spots, in years, | 10 |
| Diameter of maximum spot (Sun's = 1), | 0.05 |
| Breadth of zone of drift, at equator, direction of rotation, | 30° |
| Breadth of zone of drift,„ in each hemisphere, opposite direction, | 30° |
| Light of the Sun (light of star of 1st Mag. = 1), | 108,000,000,000 |
| Intensity of Sun's light (electric light = 1), | 4 |
| Intensity of Sun's light : (wax candle = 1), | 15,000 |
| Heat of each square foot of surface, mechanical effect, in horse-power, | 7,000 |
| Heat of each square foot of surface, equal the combustion of cwts. of coals per hour, | 13.5 |
| Heat of each square foot of surface, equal 5 lbs. matter falling with velocity per second, in miles, | 390 |
| Heat at centre of disc (heat at border = 1), | 2 |
| Diameter of largest spots, in miles, | 50,000 |
| Number of strata in atmosphere, | 4 |
| Spots seen to rotate on their axis (in days), about | 18 |
| Heat equivalent to loss of mechanical force by Mercury falling into Sun (a year's heat of Sun = 1), | 3 |
| Velocity of bodies near the Sun (miles per second), about | 400 |
| Point in Hercules to which the Sun is advancing, declination 35° N., right ascension, | 250° |
