German astronomer, b. 4 December, 1821, at (Nieder-) Cunnersdorf near Löbau, Saxony; d. 16 March, 1889, in Arcetri near Florence. Having lost his mother in early infancy, he was placed under a schoolmaster from his ninth to his fourteenth year, and employed as sexton, beadle, gardener, and collector of fees on occasions of New Year, of baptisms, and marriages. He then learned the art of lithography, and about his twentieth year, went to Copenhagen with letters of recommendation to a distant relative Lehmann, the father of the Danish statesmen and journalist, Orla Lehmann. During a three-years' stay he was a welcome and frequent guest with a number of artists and academicians. The sculpture Reinhold carved his bust, and the painter Bunsen drew his portrait. His German poems to friends and benefactors show a complete mastery of his native tongue. He became enthusiastic over the literature and national songs of the Danes, and translated selections into German, e.g., "King Réné's Daughter". These three years in Denmark were, as he used to say, his academic career. With a desire to know peoples and countries from experience, he went to Christiania, but soon turned his path to the land of the fine arts. About 1850 he settled in Venice as lithographer. The Palace of the Doge seems to have attracted his artistic tastes, for he became intimately acquainted with the family of the Porter Gambin, whose daughter Marianna he married, embracing at the same time the Catholic faith. His wife testified that Tempel had never been satisfied with his former religion and purposely chose a Catholic companion in life. The marriage proved very happy, although not blessed with children. Contact with cultured people in Venice awakened in him a taste for astronomy. From his earning he bought a 4-inch (Stienheil) comet-seeker, and in 1859 made two discoveries, one of a comet (designated 1859 I), on 2 April, and another of the Merope-Nebula in the Pleiades, on 19 October. The new talent for discoveries matured in him the plan of embracing the astronomical career. In his enthusiasm he moved to Paris, but found that lack of scientific training precluded entrance to the Imperial Observatory. Greatly disappointed by Leverrier, the director, he moved with his wife to Marseilles in 1860, where he was accepted by Benjamin Valz as assistant astronomer.

Tempel began his career in Marseilles with the discoveries of a comet (1860 IV) on 22 October, and of two minor planets on 4 and 8 March, 1861, all with his own 4-inch comet-seeker, on the terrace of the observatory. The position however lasted only half a year, owing partly, it would seem, to continued strained relations with Leverrier. He then settled down once more as lithographer without, however, giving rest to his comet-seeker. From window or garden he discovered, during ten years, no less than thirteen comets and four minor planets, more than half of them new. From Marseilles he began publishing his observations in the "Astronomische Nachrichten". In France he missed cordial and intellectual intercourse, and a literary attempt of his in "Les Mondes", in May, 1863, on the question of the variability of nebulae, was severely criticized by Leverrier. In the same year (1863) he paid a two-months' visit to his native country, spending most of the time at the observatory of Leipzig. Just two years before, in 1861, a former astronomer of Leipzig, d'Arrest, had built a new observatory at Copenhagen. Unfortunately for Tempel, d'Arrest was the very one who criticized his publication on the Merope-Nebula as exaggerated, although the controversy ended in justifying Tempel's assertion, that nebulae must be observed with low magnifying powers. Tempel's effort, in 1870, to get a position under d'Arrest was fruitless. =20

In January, 1871, the Provisional Government ordered the Germans out of Marseilles. In spite of his experiences in France, Tempel sympathized with the unfortunate country during the war. Arrived at Milan he found in Schiaparelli the man who appreciated his talents. Though he had no academic degrees, he was offered a position in the Brera Observatory. Two of Tempel's comets had attracted Schiaparelli's attention: that of 1866 (I) which furnished to him the proof of connexion with the November stream of meteors, and that of 1867 (II) which proved to revolve entirely between the orbits of Mars and Jupiter and to run almost parallel with the latter planet in 1869, so as to furnish a type specimen of planetary perturbation. Comet "1869 III" is called Tempel's "third periodic comet", but its periodicity was not recognized until 1880. Four new comets were discovered in Milan. Comet "1873 II", called Tempel's "second periodic", is remarkable for the shortness of its period, being little over five years, and second only to Encke's comet. Tempel's publication in the Milan "Ephemeris" for 1872 shows that he reduced his own observations. His mind was sufficiently mathematical to acquire the use of logarithms and trigonometry and to draw elliptical orbits. Number V of the Brera Publications contain masterly lithographic plates of a lunar eclipse (1 June, 1863), of the Merope-Nebula, of Jupiter's satellites and a series of Coggia's comet. A more perfect map of the Pleiades appeared in "Monthly Notices" (XL, 1880). Contact with Schiaparelli brought honours to Tempel. The Vienna Academy rewarded him four times for the discovery of comets, the two of 1869 discovered in Marseilles, and the two of 1871. Once in 1872, in the absence of the director, he received the Emperor of Brazil at the observatory, acted as cicerone, and presented some of his drawings. The year after, he received, through the Brazilian Consul, the diploma of "Knight of the Imperial Brazilian Order of Roses".

When, in 1873, the Arcetri Observatory lost its director Donati, by death, Schiaparelli proposed Tempel as successor. The severe winters of Milan and the prospect of an independent position made it easy for Tempel to accept, although the unfinished state of the buildings and instruments, the title and scanty salary of assistant astronomer, the lack of library and assistants, were fraught with disappointments. After four years' work in Milan (1871-74) Tempel moved to his last station, which he was to hold for fourteen years. He found the observatory situated in an earthly paradise. It was designed and commenced in 1869 by Donati, under the University of Florence, but interrupted in 1872 by Donati's sickness. For two years it had been left in this state. The rain poured in on all sides and a wall of the meridian room had to be supported. A description of the observatory is given by Tempel in the "Astr. Nachr.", CII (1882). The predecessor of Donati, Amici, had constructed two object-glasses, one of 9.4 inches and one of 11 inches, large sizes in those times, but their mountings were imperfect and incomplete. The former had a wooden stand and could only be used on the terrace; pointing to objects of over 40° altitude was found dangerous. The mounting of the largest instrument was parallactic, but without divided circles, without clock-work, without clamp and slow motion. The observing chair was a ladder that did not reach to stars within 20° of the horizon. Both instruments had only one eye-piece. The books present contained no star catalogues, and were lying on the floor. Money was still owing on the building, and no resources for the future open. The habitation was so defective that Tempel had to live in a neighbouring villa until his death.

On examination the object-glasses proved a little defective in colour correction but excellent in definition; hence less adapted for planets but perfectly suitable for comets, asteroids, and nebulae, the very programme of Tempel. Nebulae, however, became now his main field. In Arcetri he picked up only one more comet, "1877 V". The work with the large equatorial proved very slow and laborious. To find and to identify the stars, the observer had to descend from the ladder, use the comet-seeker on the terrace and make triangulations on the small charts at hand, all without electric light. And yet, after four years' work, Tempel presented to the Royal Academy of the Lincei a collection of drawings of the more interesting nebulae, which secured him the royal prize given every six years for the best astronomical work in Italy. The Academy even offered to publish the drawings, but the proofs of the lithographs did not satisfy the author. The designs are the more valuable as they contain many stars, measured with a double ring-micrometer. Tempel discovered many new nebulae, observed a number that had been neglected since Herschel's time, wrote a mass of careful notes that are not yet published, occasionally correcting errors. Extracts of his observations are found in the "Astr. Nachr." (vols. 93-113). Drawings of the Orion nebula were published in the "Astr. Nachr.", vol. LVIII (1862), and in the Memoirs of the R. Bohemian Society of 1885 (reviewed in the Vierteljahrsschrift, XXII). Tempel was elected foreign associate of the Royal Astronomical Society of England in 1881, together with Gyldén, Pickering, Tietjen, and Tisserand (Monthly Notices, XLI, 377). In 1886 he was honoured with a letter from King Humbert, handed to him by the Adjutant General, in recognition of his astronomical drawings. In the intercourse with scientific men, the lack of academic training betrayed itself occasionally, and Tempel himself regretted all his life that he had not learnt Latin. Diffusiveness of style and uncritical assertions provoked contradiction. A controversy with Dreyer, the astronomer of Birr Castle, about the reality of spiral forms in many of Lord Rosse's drawings of nebulae, may be found in "The Observatory" (vols. I-II,1878). The existence of a faint nebula drawn by Tempel (near H. I 55 Pegasi) was denied by Keeler (Astroph. J. XI, 1900).

Tempel's intercourse with old friends in Copenhagen remained cordial to his end. He received them or friends recommended by them, like brothers, and always regretted that his means did not allow him to revisit Copenhagen. His letters to them breathe a deeply religious spirit. He glories in his honesty from childhood, regrets complaining about injuries received, speaks of the blessings of Providence, of friendship beyond death, gives thanks and praises to God, promises prayers to friends and benefactors, and looks confidently towards eternity. Expressions like these made his Protestant friend say in the "Dagbladet": "During the many years' sojourn in Italy his mind, which was subject to depressions, had found peace by entering the Catholic Church". The same friend assured the writer of this article that, on a visit to Arcetri, he had found Tempel very happy in his religious convictions. His dearest company was an old priest who visited him regularly. A Franciscan from the Convent of Quaracchi was his confessor, and the Carthusians of the Certosa were his friends. Towards the end of 1886 Tempel was attacked by a liver complaint and, in the beginning of 1887, by partial paralysis. Unable to observe, he put his notes in order for publication. During his illness he received the sacraments repeatedly. The parish priest of S. Leonardo (now Canon Emilio Nunziati) testifies that Tempel was a thoroughly convinced Catholic and died a saintly death, having his mind clear to the last. Tempel was hardly sixty-eight years old. He is buried near the tomb of Donati, in the cemetery of S. Felice a Elma, a suburb of Florence. He left neither debts nor property, and his widow was provided for by what is called in Italy a "spaccio di sali e tabacchi", this again, as it seems, through Schiaparelli. More than 186 drawings of nebulae and stars, with numerous notes, are now the property of the university and deposited in the Tribune of Galileo (via Romana). A list of them is in the "Aston. Nachr." CII (1882), and in the "Bohemian Memoirs" (1885).

Dagbladet (Copenhagen, 4 April, 1889); Monthly Notices R.A.S., L (1890), 179; SCHIAPARELLI, Astron. Nachr., CXXI (1890), 95; ABETTI, Publicazioni, fasc. XXVII (Arcetri, 1909), 163; IDEM, Rivista di Astronomia, III (Turin, 1909). Private letters from Copenhagen, Armagh, and Florence.

J. G. Hagen.