HELL, MAXIMILIAN, a distinguished astronomer and member of the order of Jesuits, was born May15,1720, at Sehemnitz in Hungary, and manifested, at an early age, a decided taste for the study of natural philosophy and astronomy. At twenty-five years of age he was employed as an assistant In an observatory belonging to the Jesuits at Vienna, and he was at the same time keeper of tho museum of experimental philosophy which had just then been formed in that city. In 1746 he was made rector of an academy at Leutachau in Hungary ; but this post he held only one year, when ho returned to Vienna Hero he completed his theological studies, and received a small number of pupils, whom he instructed in mathematics. He took orders in 1751, and after three years obtained the rank of doctor, with an appointment to the professorship of mathematics at Clausenburg in Transylvanirs. Having continued in this situation four years, he again returned to Vienna, where he was established in an observatory which had been built in conformity to his own direci tions; and he held the appointment during the remainder of his life. Besides the duty of making celestial observations, he was charged with that of giving lessons in mechanics; as, in England, about eighty years earlier, the first astronomer royal was required to teach the use of nautical instruments to two boys from Christ's Hospital : the German astronomer however gave the lesions only during one year, his time afterwards being fully occupied in performing services more important to science.
Through the mediation of Count Bache, who was eent from Copen hagen for the purpose of making the proposal, lie accepted an invita tion from the court of Denmark to undertake a journey to Wardhuys in Lapland, io order to observe there the transit of Venue over the sun's disc. Accordingly he set out from Vienna in 1768; and, after staying a short time at Copenhagen, he proceeded to the place of his destination : he was absent about two years and a half on that mission, when having fully succeeded in its object, he returned to Vienna. Besides the transit, Holl took advantage of his
residence in Lapland to study the geography, the natural history, and the climate of the country ; the history, language and religion of the people, with the state of tho arts among them : he mado also nume rous observations ou terrestrial magnetism, on the phenomena of the tides and winds, and on the variations of the barometrical column ; and he measured the heights of the principal mountains. After his return ho prepared a work containing a full account of hie researches, which was to have been published in three volumes, 4to, but it never appeared.
Hell was very fortunate in the sky being favourable, on the day (June 3, 1769) that the transit took place, so that he was enabled to observe the interior contact at the commencement, and both the interior and exterior contacts at the termination of the phenomenon ; and it is a proof of the accuracy of his observations that the; value of the sun's parallax, which he deduced by comparing them with the corresponding observations at certain other places, agreed, within one fifth of a second, with the value afterwards determined from compa risons with all the best observations which were made.
On accepting the engagement, Hell was enjoined by the Danish ministry to abstain from publishing any account of his observations till his return to Copenhagen, and till he had made all the requisite computations. The delay which, in consequence of this injunction, took place in making Hen observations public, gave offence to Lalande, who had, by letters addressed to the different governments of Europe, greatly promoted the measure of observing the phenome non at different places on the earth's surface ; the two astronomers were however soon reconciled, and they continued to correspond with each other as before. Hell drew up a memoir relating to the transit, which was read before the Academy of Sciences of Copenhagee, November 24, 1769.