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The sun revolving on his axis turns,
And with creative fire intensely burns;
Impell'd the forcive air, our earth supreme
Rolls with the planets round the solar gleam:
First Mercury completes his transient year,
Glowing refulgent; with reflected glare;
Bright Venus occupies a wider way;
The early harbinger of night and day;
More distant still our globe terraqueous turns,
Nor chills intense, nor fiercely heated burns.
Around her rolls the lunar orb of light,
Trailing her silver glories through the night:
Beyond our globe the sanguine Mars displays
A strong reflexion of primeval rays;
Next belted Jupiter far distant gleams,
Scarcely enlighten'd with the solar beams;
With four unfix'd receptacles of light

He tow'rs majestic through the spacious height;
But farther yet the tardy Saturn lags,
And seven attendant luminaries drags;
Investing with a double ring his pace,
He circles through immensity of space.



Of the Figure of the Earth.

TUTOR. Having, in our last Conversation, given you a description of the Solar System in general, we will now proceed to consider each of its parts separately: and since we are most of all concerned with the earth, we will begin with that body.

James. You promised to give us some reasons why this earth must be in the form of a globe, and not a mere extended plane, as it appears to common observation.

Tutor. Suppose you were standing by the sea-shore, on a level with the water, and at a very considerable

distance, as far as the eye can reach, you observe a ship approaching, what ought to be the appearance, supposing the surface of the sea to be a flat plane?

Charles. We should, I think, see the whole ship at once, that is, the hull would be visible as soon as the top-mast.

Tutor. It certainly must, or indeed rather sooner, because the body of the vessel being so much larger than a slender mast, it must necessarily be visible at a greater distance.

James. Yes, I can see the steeple of a church at a much greater distance that I can discern the iron conductor which is upon it, and that I can perfectly see long before the little piece of gold wire, which is fixed at its extremity, is visible.

Tutor. Well, but the top-mast of a vessel at sea is always in view some

little time before the hull of the ves sel can be discerned. Now, if the surface of the sea be globular, this ought to be the appearance, because the protuberance or swelling of the water between the vessel and the eye of the spectator, will hide the body of the ship some time after the pendant is seen above.

Charles. In the same way as if a high building, a church for instance, were situated on one side of a hill, and I was walking up on the opposite side, the steeple would come first in sight, and as I advanced towards the summit, the other parts would come successively in view.

Tutor. Your illustration is quite to the purpose in the same way two persons, walking up a hill on the opposite sides, will perceive each other's heads first; and as they advance to

the top, the other parts of their boIdies will become visible. With respect to the ship, the following figure will convey the idea very accurately.


Suppose C A B represent a small part of the curved surface of the sea; if a spectator stand at B, while a ship is at C, only a small part of the mast is visible to hin, but as it advances, more of the ship is seen, till it arrive at e, when the whole will be in sight:

Behold when the glad ship shoots from the port
Upon full sail, the hulk first disappears,
And then the lower, then the higher sails;
At length the summit of the tow’ring mast
Alone is seen: nor less, when from the ship
The longing sailor's eye in hope of shore:

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