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HISTORY OF PHYSICAL ASTRONOMY.

the immortal author of the disoovery forms one of the brightest orna-ments*.

While Bradley was prosecuting his admirable observations at Green-wich , the Continent was adorned by two astronomers who are justlyentitled to be associated in the history of astronomy with their illustriouscontemporary. It will be desirable, before proceeding further, to presentthe reader with a brief notice of their labours.

Nicholas Louis de Lacaille was born at Rumigny, near Rosoy, inFrance , on the 15th of March, 1713. He was destined by his parentsfor the church, but his inclination towards astronomical studies effectuallyfrustrated their design. In 1713 he proceeded to Paris , where he waskindly received by J. Cassini, who assigned to him a situation in theRoyal Observatory. In 1738 he was employed, in conjunction with theyounger Maraldi, in surveying the western provinces of France . In thetwo following years he took an active part in the operations connectedwith the verification of the French arc of the meridian, and it is to hisenergy and skill that the successful prosecution of that important un-dertaking is mainly to be ascribed. While engaged in these labours hewas appointed Professor of Mathematics in the Mazarine College of Paris ,whither he retired at their conclusion. A small observatory having beenfitted up for his use at the college, he continued to labour there forseveral years, dividing his time between his professional duties and astro-nomical pursuits. In 1750 he proceeded to the Cape of Good Hope , forthe purpose of making observations in the southern hemisphere . Duringhis residence there, he amassed materials for determining the parallaxesof the Moon, Venus, and Mars , and for investigating the laws of refrac-tion. He also measured an arc of the meridian, and the length of thesecond’s pendulum, besides observing ten thousand stars in the southernhemisphere. Upon his return to Europe , in 1759, he established himselfin his former place of residence, where he proceeded to deduce a numberof important results from his observations. In 1757 he published afundamental catalogue of stars, forming one of the most valuable contri-butions made to astronomical science during the eighteenth century. Inthe following year he published his solar tables, the elements of whichwere determined with such precision as to leave little further to be de-sired. These are the earliest solar tables in which the effects of planetaryperturbation are taken into account. He is also the author of a catalogueof about 500 zodiacal stars, which was published after his death.

The advantages which Lacaille enjoyed in the prosecution of his labourswere extremely moderate. He had no assistant to relieve him from aportion of the drudgery incidental to astronomical pursuits, nor were hisinstruments by any means so perfect as those of some of his contempo-raries. By his talents and perseverance, however, he succeeded in over-coming these difficulties; but, unfortunately, he fell a victim to incessantapplication, when he had only attained an age at which the human consti-tution usually retains its full vigour. He died on the 21st of March,1762, in the 49th year of his age.

When the admirable labours of Lacaille are taken into consideration, itis impossible to repress a feeling of regret that he was not placed in a

* “Miscellaneous Works and Correspondence of the Rev. James Bradley , D.D.,F.R.S.,” 4to., Oxford, 1832.