he annexed the latitude, and longitude, it had at that time.

Did Hipparchus make any other discoveries? Yes; he ascertanied that the interval between the vernal, and autumnal equinox, is 186 days, that is, seven days longer than between the autumnal and the vernal.

What is the cause of this difference?

The eccentricity of the earth's orbit. He also discovered that slow motion of the stars from east to west, which is now denominated the precession of the equinoxes.

You have already mentioned to me the Ptolemaic system. How was the individual distinguished, whose name this system bears ?

He is distinguished by having been an indefatigable collector, and recorder, of the opinions of others, and a most diligent observer of the heavens.

When did he flourish?

In the first century of the Christian æra. Will you not tell me a little more about the Ptolemaic system ?

It is, I believe, only necessary that I should add, that, above the planets before mentioned to you, he placed the firmament of fixed stars, the crystalline orbs, the primum mobile, and the heaven of heavens, all which, according to his belief, revolved round the earth in 24 hours,

c 2

and also in certain periodical times, agreeably to their annual changes.

And what opinion do you form of this system?

It must, notwithstanding the erroneous principles upon which it is founded, be considered a wonderful proof of human genius and exertion.

Did Ptolemy make any important disco. veries?

No: but he completed and improved the catalogue of fixed stars begun by Hipparchus ;and he ascertained that the equinox proceeds at the rate of one degree in one hundred years.

Since Ptolemy was a faithful collector of the opinions of others, has he any observations, which may confirm the idea that our sphere is originally Chaldean ?

In his work he asserts, that Hipparchus collected all the accounts of eclipses which he' could meet with among the Babylonians, and all their celestial observations. Being preserved by Ptolemy, they were handed down unimpaired to us; so that from Hipparchus, through the care of Ptolemy, we are in possession of the Chaldean astronomy, and our sphere is, in point of fact, not Egyptian, but Chaldean.

Who was the next person that distinguished himself by his attention to astronomy?

From the time of Ptolemy, to the period when his valuable work, consisting of the labours and discoveries of all his predecessors,

was translated from Greek into Arabic, a long and gloomy interval of nearly 700 years elapsed, without one material improvement being made in this noble science, either in the schools of Egypt, or Greece. Since the respectable list of ancient astronomers terminated with Ptolemy, we will discontinue our inquiries for the present, and this protracted conversation, itself shall find a close.

CHAPTER III.

A CONTINUATION OF THE SAME SUBJECT.

May I renew our conversation by inquiring,

what circumstances led to a revived attention to astronomy?

But will it not be interesting to you, first to learn, what could have occasioned the neglect of such a delightful subject?

Yes; that would be very agreeable.

Well, then, you must call to mind the fact, that at the period during which astronomy was neglected, a remarkable revolution was taking place in the world. Rome, the mistress of all nations, the sovereign arbitress of the fates of men, was hurled from her exalted pinnacle.

I have read, that the Roman empire had become too extensive to be guided by one hand, however powerful that hand might be.

That is true; but the hand which held the reins of government, was not strong, as it had been; it was become weak, through the luxury and effeminacy of those, who were once all manliness to defend the cause at home, all energy to support her dignity abroad.

Perhaps then it was this obvious love of ease

among the Romans, that encouraged the barbarians to make their attack?

This certainly was not overlooked by them, and the martial spirit, and irresistible impetuosity of the Ostrogoths, and Visigoths, of the Huns, Saxons, and Franks, form an astonishing contrast with the timid policy, the delicate refinements, and the divided opinions, of the now, degenerate Romans.

But, of course, while you speak well of these barbarians, as being fine-spirited men, you surely think they did great injury to science?

Of this there can be but little doubt: for, though the Romans were sunk to the lowest state of national degradation, and therefore were not qualified to illustrate to their invaders the advantages of their laws, their arts, their literature, and sciences; yet, even if they had, perhaps the barbarians were too ignorant, rightly to have appreciated them; and their desolating fury, produced a revolution too much like an overwhelming torrent, to allow of the revival of the old Roman spirit, or the melioration of barbarian impetuosity. In consequence, indeed, of the extinction of freedom, the old Roman spirit had, in fact, completely evapo

rated.

Then it is to this sudden change in the state of the world, that I am to ascribe the neglect of astronomy?