Om Poncelets' Betydning for Geometrien . Udgivet som Universitets-Program for 1ste Halvaar 1879 ved S. Lie. COPY SIGNED

In-8° broché, 146 pp Elling Bolt Holst (19 July 1849 - 2 September 1915) was a Norwegian mathematician, biographer and children's writer. Holst was born in Drammen, Norway. He was a son of bookseller Adolph Theodor Holst and Amalie Fredrikke Bergh. He was a grandson of merchant and politician, member of the Storting, Elling Mathias Holst (1785-1852). Holst enrolled as a student at the University of Christiania (now University of Oslo), his doctoral advisor was Sophus Lie, and he graduated as cand.real. in 1874. He continued his studies in Germany, where Felix Klein was among his teachers. He was appointed teacher at Aars og Voss skole in Christiania (now Oslo). His thesis Et par syntetiske Methoder, især til Brug ved Studiet af metriske Egenskaber was finished in 1882. Holst lectured in mathematics at the University of Oslo from 1894. Among his other mathematical works are his contribution from 1878, Om Poncelets betydning for geometrien, and several course books. He wrote biographies of several mathematicians, including Cato Maximilian Guldberg, Carl Anton Bjerknes, Sophus Lie and Niels Henrik Abel. Holst is particularly known for his children's books Norsk Billedbog for Børn, three collections from 1888, 1890 and 1903 (with illustrations by Eivind Nielsen). The first of these books has been called Norway's first national picture book (although a picture abc had been published previously, in 1876). Holst started collecting traditional poems for children, several of which were first published in Norwegian writing in these books. These poems, such as "Ride, ride ranke", "Bake kake søte", "Kjerringa med staven", "Hoppe! sa gåsa" and "Du og jeg og vi to", have had a constant popularity over many years, and Norsk Billedbog for Børn has been reissued several times. Also contemporary poetry was included in the books, such as some poems by Henrik Wergeland, "Kom bukken til gutten" by Bjørnstjerne Bjørnson, and "Blaamand" by Aasmund Olavsson Vinje. Among his other children's books are Julegodter for Børn from 1892, and A.B.C. for Skole og Hjem from 1893 (together with Anna Rogstad).He published the picture book Fra Sæteren in 1899, with illustrations by Lisbeth Bergh. - - - - - - - - - - - - Jean-Victor Poncelet naquit le 1er juillet 1788, à Metz, une place-forte des Trois-Évêchés. Il rejoignit la Grande Armée de Napoléon en juin 1812 comme lieutenant du génie pendant la campagne de Russie, à Vitebsk. Assurant la protection de l'armée du Maréchal Ney, il fut fait prisonnier à la Bataille de Krasnoï, le 18 novembre (son colonel avait été tué et il eut un cheval tué sous lui), et fut conduit à Saratov, sur la Volga, soit près de 1 500 kilomètres qu'il parcourut à pied en quatre mois (de novembre à février), en plein hiver russe. Privé de tout livre, il reprit les fondements des mathématiques. C'est alors qu'il mit en forme les principes fondamentaux de la géométrie projective qui avaient été approchés jadis par Pappus (ive siècle), puis Girard Desargues et Pascal. Le retour en France prit lui aussi quatre mois. De retour en France, en 1814, il fit paraître en 1822 son Traité des propriétés projectives des figures qui allait lancer pendant tout le xixe siècle les mathématiques sur la voie de la géométrie pure. Élève de Gaspard Monge, il rénova la géométrie projective (1822) (théorème de Poncelet sur les coniques, dualité par pôles et polaires réciproques, faisceau harmonique, points cycliques). Il aurait introduit dans les écoles de France, à partir de 1814, l'usage du boulier dans un but éducatif, à la suite de son retour de Russie où il avait découvert le Stchoty utilisé par les Russes. Il s'intéresse aussi à la mécanique et présente en 1824 son invention de la « roue hydraulique à aubes courbes », qui sera distinguée par le prix Montyon de l'Académie des sciences l'année suivante.…