The Study of Astronomy, adapted to the capacities of youth / In twelve familiar dialogues, between a tutor and his pupil: explaining the general phænomena of the heavenly bodies, the theory of the tides, &c.

by teacher of astronomy John Stedman

“And where the earth’s high surface joins the skies,

“Where stars first set, and first begin to shine,

“There draw the fancy’d image of this line.”

Pupil. A very pleasing description, indeed.

Tutor. You will remember that this is called the rational horizon; but that which respects land and water is called the sensible horizon. The former divides the heavens into two equal parts, and is 90 degrees distant from a point directly over our heads, called the zenith, and the opposite point of the heavens directly under our feet, called the nadir.—But I must resume the subject of the atmosphere.

Pupil. Had I not thought you had finished your description of the atmosphere, I should not have presumed to interrupt you.

Tutor. What I have told you respecting the horizon is necessary for you to be acquainted with; therefore, the suspension is immaterial.—You must, I make no doubt, have observed the sun and moon at rising and setting to appear larger than when higher above the horizon.

Pupil. I have, frequently, Sir.

Tutor. And cannot you tell the reason of it?

Pupil. No, Sir.