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suns to light me rise,

My footstool earth, my canopy the skies."

POPE.

But do these worlds display their beams, or guide
Their orbs, to serve thy use, to please thy pride?
Thyself but dust, thy stature but à span,

A moment thy duration; foolish man!
As well may the minutest emmet say,
That Caucasus was rais'd to pave his way:
The snail, that Lebanon's extended wood
Was destin'd only for his walk and food:
The vilest cockle, gaping on the coast
That rounds the ample seas, as well may boast,
The craggy rock projects above the sky,

That he in safety at its foot

may

lie:

And the whole ocean's confluent waters swell

Only to quench his thirst, or move and blanch his

shell.

PRIOR

CONVERSATION XIX.

TUTOR.

Of Venus.

We now proceed to Ve

nus, the second planet in the order of the solar system, but by far the most beautiful of them all:

Fairest of stars, last in the train of night,
If better thou belong not to the dawn,

Sure pledge of day, that crown'st the smiling morn
With thy bright circlet, praise him in thy sphere,
While day arises, that sweet hour of prime.

MILTON.

James. How far is Venus from the sun?

Tutor. That planet is 68 millions of miles from the sun, and she finishes her journey in 224 days, conse

quently she must travel at the rate of 75,000 miles in an hour.

Charles. Venus is larger than Mercury, I dare say?

Tutor. Yes, she is nearly as large as the earth, which she resembles also in other respects, her diameter being about 7700 miles in length, and she has a rotation about her axis in 23 hours and 20 minutes. The quantity. of light and heat, which she enjoys from the sun, must be double that which is experienced by the inhabitants of this globe.

James. Is there also a difference in her seasons, as there is here?

Tutor. Yes, in a much more considerable degree. The axis of Venus inclines about 75 degrees, but that of the earth inclines only 23 degrees, and as the variety of the seasons in every planet depends on the

degree of the inclination of its axis, it is evident that the seasons must vary more with Venus than with us.

Charles. Venus appears to us larger sometimes than at others.

Tutor. She does; and the great variations of the apparent diameter of Venus demonstrate that her distance from the earth is exceedingly variable. It is largest when the planet passes over the disk of the sun; that is, as we shall soon see, when there is a

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transit. Suppose s to be the sun, T

the earth in her orbit, and a, b, c, d, e, f, Venus in hers: now it is evident that when Venus is at a, between the sun and earth, she would, if visible, appear much larger than when she is at din opposition.

James. That is because she is so much nearer in the former case than in the letter, being in the situation a but 27 millions of miles from the earth T, but at d she is 163 millions of miles off.

Tutor. Now, as Venus passes from a, through b, c, to d, she may be observed, by means of a good telescope, to have all the same phases as the moon has in passing from new to full; therefore when she is at d she is full, and is seen among the fixed stars: during her journey from d to e, she proceeds with a direct motion in her orbit, and at e she will appear to an

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