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"The elliptical circle being supposed to be the Earth's orbit, with the Sun, S, in one of the foci. Now the spaces, 1, 2, 3, etc., though of different shapes, are of the same dimensions, or contain the same quantity of surface. The Earth, we have already seen, in its journey round the Sun, describes an ellipse, and moves more rapidly in one part of its orbit than in another. But whatever may be its actual velocity, its comparative motion is through equal areas in equal times. Thus its center passes from E to C, and from C to A, in the same period of time, and so of all the other divisions marked in the figure." —Comstock, 1850

Elliptical Orbit

"The elliptical circle being supposed to be the Earth's orbit, with the Sun, S, in one of the foci.…

Sir William Herschel, famous English astronomer

Sir William Herschel

Sir William Herschel, famous English astronomer

"Relative distance of the Planets. Having now given a short account of each planet composing the solar system, the relative situation of their several orbits, with the exception of those of the Asteroids, are shown in this figure. The orbits are marked by the signs of each planet, of which the first, or that nearest the Sun, is Mercury, the next Venus, the third the Earth, the fourth Mars then come those of the Asteroids, then Jupiter, then Saturn and lastly Herschel." —Comstock, 1850

Planet Distance

"Relative distance of the Planets. Having now given a short account of each planet composing the solar…

"Circular Motion of the Planets." —Comstock, 1850

Planet Motion

"Circular Motion of the Planets." —Comstock, 1850

"Elliptical Orbits.—It has been supposed that the Sun's attraction, which constitutes the Earth's gravity, was at all times equal, or that the Earth was at an equal distance from the Sun, in all parts of its orbit." —Comstock, 1850

Planet Motion

"Elliptical Orbits.—It has been supposed that the Sun's attraction, which constitutes the Earth's…

"The comparative dimensions of the planets." —Comstock, 1850

Planet Sizes

"The comparative dimensions of the planets." —Comstock, 1850

"These telescopes were all reflectors; that is, instead of looking up at a star through a tube with a glass in the upper end [Herschel] would look down into the tube away from the star and see its reflecting in a concave mirror at the lower end of the tube."—The Foundation Library, 1911

A Great Reflecting Telescope

"These telescopes were all reflectors; that is, instead of looking up at a star through a tube with…