the earth 65,000 miles; Venus 75,000 miles; and Mercury at the rate of 105,000 miles in an hour. But here we come to a comet whose progressive motion in that part of its orbit which is nearest to the sun, is more than equal to eight times the velocity of Mercury.

Charles. Were not comets formerly dreaded, as awful prodigies intended to alarm the world?

Tutor. Comets are frequently accompanied with a luminous train called the tail, which is supposed to be nothing more than vapour rising from the body in a line opposite to the sun, but which, to uninformed people, has been a source of terror and dismay, and to this opinion many of our poets have alluded:

-Where the train

Of comets wander in eccentric ways

With infinite excursion through th' immense
Of ether, traversing from sky to sky

Ten thousand regions, in their winding road

Whose length to trace imagination fails;
Various their paths-

While distant orbs with wonder and amaze

Mark their approach, and night by night alarm'd
Their dreaded progress watch, as of a foe
Whose march is ever fatal, in whose train
Famine and war, and desolating plague,
Each on his pale horse rides, the ministers
Of angry Heaven to scourge offending worlds!

MALLET'S EXCURSION

Ff2

CONVERSATION XLVI.

Of the Sun.

TUTOR. Having given you a particular description of the planets which revolve about the sun, and also of the satellites which travel round the primary planets as central bodies, while they are carried at the same time with these bodies round the sun, we shall conclude our account of the solar system by taking some notice of the sun himself,

Informer of the planetary train,

Without whose quick'ning glance their cumbrous orbs

Were brute unlovely mass, inert and dead,

And not, as now, the green abodes of life.

THOMSON'S AUTUMN, line 1086.

Fames. You told us a few days ago, that the sun has a rotation on its axis, how is that known?

Tutor. By the spots on his surface it is known that he completes a revolution from west to east on his axis in about twenty-five days, two days less than his apparent revolution, in consequence of the earth's motion in her orbit, in the same direction.

Charles. Is the figure of the sun globular? Tutor.

No; the motion about its axis renders it spheriodical, having its diameter at the equator longer than that which passes through the poles.

The sun's diameter is equal to 100 diameters of the earth, and therefore his bulk must be a million of times greater than that of the earth, but the density of the matter of which it is composed is four times less than the density of our globe.

We have already seen that by the attraction of the sun, the planets are retained in their orbits, and that to him they are indebted for light, heat and motion:

Fairest of Beings! first created light:

Prime cause of beauty! for from thee alone
The sparkling gem, the vegetable race,

The nobler worlds that live and breathe their charms,

The lovely hues peculiar to each tribe,

From thy unfailing source of splendour draw!
In thy pure shine, with transport I survey
This firmament, and these her rolling worlds
Their magnitudes and motions.-