Astronomy Without a Telescope: Being a Guide-book to the Visible Heavens, with All Necessary Maps and IllustrationsGeorge & C.W. Sherwood, 1869 - 104 σελίδες |
Δημοφιλή αποσπάσματα
Σελίδα 29 - The circumference of every circle is supposed to be divided into 360 equal parts, called degrees...
Σελίδα 126 - March, . . .1 April, . . .2 May, ... 3 June, . . .4 July, . . .5 August, . . 6 September...
Σελίδα 126 - Add 9 to the given year, and divide the sum by 28, the remainder is the year of the solar cycle ; if there be no remainder, the solar cycle is 28.
Σελίδα 133 - Now this law (that the squares of the times are proportional to the cubes of the distances) was discovered by Kepler, long before the theory of gravitation was invented, to hold in regard to the times and distances of the planets in their revolutions round the sun. Moreover, in regard to the four satellites of Jupiter the same law holds. For we are able without difficulty to observe their...
Σελίδα 126 - Number marks the position of the year in this cycle of nineteen. The Solar Cycle is a period of twenty-eight years, so called because in the twenty-eighth year after any year which may be taken all the days of the week fall on the same days of the month, as they fall in that year. One of these cycles was finished in 1807, and 1873 is the sixth year in the next cycle.
Σελίδα 27 - ... of gravity is made to coincide in principle, with its actual operation when unrestrained ; while at the same time the bodies submitted to its action move with velocities which can be readily followed by the eye. 11. Numerous facts in Geology strongly indicate that at some remote periods of duration, the position of the earth's axis with regard to the plane of its orbit was different from what it is at present, and that successive periods of change have at length brought it to its present angle...
Σελίδα 126 - But if that sum is above 30, the excess in months of 31 days, or the excess above, 29 in a month of 30 days, shows the age or days since the last conjunction. The moon's age taken from 30, leaves the day of the next new moon. When the solar and lunar cycles begin together, the moon's age on the first of each month, or the monthly epacts, are called the numbers of the month ; and are as follows, viz. For Jan. Feb. Mar. April May June These 021 234 For July Aug.
Σελίδα 25 - ... direction opposite to the direction of that wind which it is intended to supply. The direct and counter currents are also made to move in sort of spiral or loxodromic curves, turning to the west from the Poles to the Equator, and in the opposite direction from the Equator towards the Poles. This motion is caused by the motion of the earth on its axis. The earth, we know, moves from west to east. Now, if we imagine a particle of atmosphere at the North Pole, where it is at rest, to be put in motion...
Σελίδα 147 - Then Horomazes, having magnified himself to three times his size, removed himself as far from the sun as the sun is distant from the earth, and adorned the heaven with stars; and one star, Sirius, he established above all others as a guardian and watcher.
Σελίδα 128 - C, and a2 = 62 + c2 — 2bc cos A. 14. In any triangle to prove that the sines of the angles are proportional to the opposite sides, ie that sin A_ sin B _ sin O "~a E ~ — AD In Fig.