HISTORY OF PHYSICAL ASTRONOMY.

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ascension, representing the relative positions of all the telescopic starsdown to the tenth magnitude. On the 13th of August, 1847, while sur-veying the heavens in the prosecution of these labours, his attention wasdrawn to a star of the 8.9th magnitude, which was not marked in Hora xix.of the Berlin Maps constructed by Wolfer. He was especially surprised tofind that, although the same region had been examined on the 22nd of June,and also on the 31st of July, no note had been made in reference to the un-marked star. Even this circumstance, however, was not considered by him toafford conclusive proof in favour of a proper motion of the star, since it ap-peared to him not improbable that the previous invisibility of the star mightarise from its light being variable, having met with a great many newstars of this nature in the course of his observations. The application ofthe micrometer, however, dispelled all doubts on this point. Before halfan hour elapsed he was enabled to satisfy himself, by its change of position,that the star had a proper motion. Subsequent observations shewed thatit was one of the ultra-zodiacal planets. At the suggestion of Mr.Bishop, the planet was named Iris. On the 18th of October of the sameyear, Mr. Hind discovered a star of the tenth magnitude, which was notmarked in Hora v. of the Berlin Maps. Micrometrical measures of itsposition, made after the lapse of about three hours and a half from thetime when he first observed it, established the existence of a propermotion. It proved to be another planet of the same class with Iris.Sir John Herschel , having been invited to name the planet, conferred onit the appellation of Flora. The discovery of the two planets Irisand Flora reflects equal credit on the assiduity of Mr. Hind, and on theenlightened zeal of the gentleman under whose auspices he has beenprosecuting his observations. It is pleasing to reflect, that in recent timesthe British Isles have furnished a greater number of examples of thedevotion of private resources to the cause of astronomical science than anyother country.

The planet Flora formed the eighth fragment of the hypothetic planetof Olbers which had been discovered since the commencement of thepresent century. Two more have subsequently been added to thisnumber. One of them was discovered on the 25th of April, 1848, byMr. Graham, of Mr. Cooper's Observatory, Markree, Ireland . It hasreceived the name of Metis . This planet is remarkable for the near coin-cidence of its mean motion with that of Iris, the difference of theirperiodic times having been found by the most recent calculations toamount only to five days. The other planet was discovered at Naples, onthe 16tli of April, 1849, by M. De Gasparis. At the suggestion of Sig.Capocci it has been called Hygeia. This makes ten fragments of theshattered planet which have been already recovered. When it is con-sidered that, since the discovery of six of these fragments, an equalnumber of years has not yet come to a close, it may reasonably be pre-sumed that a long period is not destined to elapse before many moresimilar discoveries will be made.

When Jupiter is observed with a telescope of considerable power,there appear several obscure belts encompassing his body. Thesebelts have been found to vary in number, magnitude, and mutualdistance; but for the most part three only are observed, extendingin parallel directions across the centre of the disk. These pheno-mena escaped the observations of Galileo, his telescopes not being

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