The earliest rudiments of the Astronomical Observatory are as little known as the earliest discoveries in astronomy itself.

When the sun is compared with the earth the bulk of our luminary becomes still more striking.

The ships in dock could not get out; the ships outside could not get in; and the maritime commerce of the world would be thrown into dire confusion.

The sun has set, the moon has not risen; a cloudless sky discloses a heaven glittering with countless gems of light.

The sun and the moon, the planets and the comets, the stars and the nebulæ, all alike are subject to this universal law, which is now to engage our attention.

The question is still unsettled, but the planet cannot at present be found.

The existence of Mercury was certainly quite a familiar fact in the time of Copernicus, and therefore we must look to some earlier epoch for its discovery.

There is no better way of actually seeing that the surface of the ocean is curved than by watching a distant ship on the open sea.

This beautiful planet offers many features for consideration besides those presented by its physical structure.

The orbits of this group of bodies differ in remarkable characteristics from those of the larger planets.