JOSEPH PIAZZI was born at Ponte, at the foot of the Alps, in 1746. At eighteen years of age, he entered the order of the Theatines, a class of Catholic priests, at Milan, and studied at Milan, Turin, and Rome. In 1770, being twenty four years of age, he was appointed professor of mathematics at the new university in Malta, on the abolition of which he returned to Italy, and in 1780 became professor of the higher mathematics at Palermo. He inspired the viceroy of Sicily with the desire to improve an old tower in the palace of the kings of Sicily at Palermo, by building upon it an observatory. For his own improvement, he felt the necessity of visiting the large observatories, and becoming acquainted with the most celebrated astronomers. He arrived at Paris in January, 1787, being now forty one years of age, to pursue the study of astronomy under the celebrated Lalande. Lalande had now been for twenty five years astronomical professor at the Collége de France, where he knew how to give to his lectures a peculiar attraction. His lecture room was a kind of nursery, from which a multitude of his scholars were transplanted to domestic and foreign observatories. Here Piazzi not

merely received the benefit of the instructions of Lalande, but formed a friendship which lasted through life. In 1788 he visited England, where he ordered of Ramsden the best instruments for his observatory. Among them was a circle of five feet diameter, an instrument both new and ingenious in its construction, which Lalande characterized as forming an epoch in astronomy. Piazzi informs us that Ramsden twice undertook the construction of this instrument, and as often abandoned it; but at length in January, 1788, he entered upon the work in earnest, and finished it in August, 1789. It is an altitude and azimuth instrument, the azimuth circle being of three feet diameter, the vertical circle, as already stated, of five feet.

The latter is divided to six minutes, and has two microscopes, each reading to a single second of

arc.

In 1789, Piazzi returned to Sicily with his instruments. His observatory was completed, and he entered upon his new duties with all the enthusiasm of youth. His first observations were published in 1792. He soon after began his catalogue of stars, and dedicated the first, containing six thousand seven hundred and eighty four stars, to the Institute

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at Paris. On the evening of January 1, 1801, he was occupied as usual with his catalogue, and while observing the eighty seventh star of Lacaille's Zodiacal Catalogue, be tween Aries and Taurus, he saw close by it a star of the eighth magnitude, which he also observed.* "At that time," he informs us, doubt arose in regard to the nature of it; but on the evening of the 2d, having repeated my observations, and finding that they did not correspond either in time or zenith distance, I suspected that some error had been committed in my observations on the preceding day. I then began to entertain some idea that it might perhaps be a new star. On the evening of the 3d, my conjecture was confirmed, as I assured myself that it was not a fixed star. However, before I would speak of it, I waited till the evening of the 4th, on which I had the satisfaction of finding that it had moved according to the same laws which it had observed on the preceding days. From the 4th to the 10th, the sky was overcast. On the evening of the 10th, it appeared to me in the telescope accompanied by four oth. ers nearly of the same magnitude. I observed them all as well as possible, and comparing these observations with others which I made on the evening of the 11th, I easily distinguished the new one from the rest by its motion. I was however exceedingly anxious to see it when not on the meridian, and therefore employed myself in examining it with great care; but notwithstanding all my exertions and those of my assistants, both possessing excellent sight and accustomed to viewing the heavens with a tele

scope, it was not possible to distinguish it from many others by which it was surrounded. I was therefore obliged to be contented with seeing it on the meridian for the short space of about two minutes, that is, during the time it employed to pass over the field of the telescope; the other observations made at the same time not permitting me to remove the instrument from its position. To render these observations however more certain, while it was observed by myself with a circle, it was observed at the same time by Carioti with a transit instrument. Thus the heavens being constantly nebulous, and often obscured by thick clouds, our observations were frequently interrupted till the 11th of February; after which the star having approached very near to the sun, it was no longer possible to see it at the time of its passing the meridian. I resolved then to search for it beyond the meridian by means of azi. muths; but having fallen ill on the 13th of February, I was not able to make any further observations."

Piazzi wished to enjoy the pleas. ure of calculating the orbit of his comet, and still secure the honor of first discovery. On the 24th of January, he therefore sent to M. Oriani at Milan, and Bode at Berlin, two observations, viz. those of Jan. 1st and 23d, a number insufficient for determining an orbit. He added merely that the comet was stationary on the 10th. Oriani, finding that it had no nebulosity like comets, and that it had been sta tionary and retrograde within a short period like planets, calculated its orbit for a circle. Baron de Zach at Gotha did the same, and on the 24th of May sent his elements to Lalande. He thought at first it might be the comet of 1770, or the long expected planet between Mars and Jupiter.

Lalande, having heard of the discovery of the comet at Palermo, wrote to Piazzi for a copy of his

observations. Piazzi replied, "I had resolved to cornmunicate my observations to no one before I had deduced the elements of the comet; but it is you who claim them; I can no longer object; here they are." (C'est vous qui me les demandez, je n'ai plus d'objection: vous les trou. verez ci-jointes.) Burckhardt at Paris, immediately commenced the computation of an orbit. He soon found that a parabola would not satisfy the observations, and he was the first to obtain an elliptic orbit. Piazzi meanwhile was proceeding with his computations. He made trial of a parabolic orbit, but without success. He however obtained a circular orbit which succeeded much better than the parabola. For a long time Piazzi persisted in the opinion that he had discovered a comet, but finding that its orbit was so nearly circular, he was satisfied to call it a planet, and named it Ceres, from the tutelary goddess of Sicily.

The planet was no where seen but at Palermo before conjunction; yet astronomers throughout Europe, were prepared to search for it as soon as possible after conjunction, and Baron de Zach published a chart showing the track which the planet should pursue according to the elliptic elements. Still for nearly a year the new planet was not found; and about the close of 1801, Delambre thus addressed the Institute of France. "The star discovered about a year ago by Piazzi, has hitherto escaped the researches of all astronomers. Resembling in respect of light a star of the seventh or eighth magnitude, it exhibited none of those appearances that serve to distinguish comets. It need excite no surprise that nine months after its disappearance to Piazzi, all the astronomers of Europe should have failed in their researches, since there is an uncer tainty of some degrees respecting the exact place where it is necessary to search for it, as the elements of its orbit, calculated on so small an

arc, can not after so long an interval give the apparent places with sufficient accuracy."

Understand the nature of the dif ficulty. The planet had been observed for a period of forty days, yet during this time it had described an arc of only four degrees in the heavens. Now the accuracy of a calculated orbit depends more upon the arc described, than upon the interval between the observations; yet from this small base line of four de grees, was to be computed the planet's place after the interval of a year. It might now be in nearly the opposite quarter of the heavens. To this uncertainty of the orbit, was to be added the faintness of the star. It could only be seen with a good telescope, and could not be distinguished in appearance from a fixed star of the same brightness. An observer might thus sweep over the planet a hundred times, see it distinctly, and not be aware what he had seen. It was only by observing it on successive evenings, and detecting a change of place, that it could be identified. This required a minute. and oft-repeated examination of eve. ry faint star in the heavens within the region where the planet might possibly be found. Thus the planet was lost, and its rediscovery promised to demand a labor equal to that of original discovery. One might set about the discovery of a new planet with about as good encour agement as he could prosecute the search for the lost Ceres.

Thus every mathematician of Europe, had failed to obtain a satisfac. tory orbit. Shame on the astronomers of the nineteenth century! that so small a body should defy your combined powers! But is it not possible that we have been imposed upon? No one out of Palermo, ever saw this new star. Bode and Lalande, Oriani and De Zach, sought for it in vain. Who knows but Piazzi might have manufactured his observations from his own fertile