Moral Aspects of Labour Unions
Jean-Baptiste-Henri Dominique Lacordaire
Lucius Caecilius Firmianus Lactantius
René-Théophile-Hyacinthe Laennec
Marie Madeleine Pioche de la Vergne, Comtesse de La Fayette
Louis-François Richer Laflèche
Jean de La Haye (Jesuit Biblical scholar)
Jean-Baptiste-Pierre-Antoine de Monet, Chevalier de Lamarck
Lamb in Early Christian Symbolism
Jacques and Jean de Lamberville
Jean-Marie-Robert de Lamennais
Louis-Christophe-Leon Juchault de la Moricière
Archdiocese of Lanciano and Ortona
Land-Tenure in the Christian Era
The Duke of La Rochefoucauld-Liancourt
Henri-Auguste-Georges du Vergier, Comte de la Rochejacquelein
René-Robert-Cavelier, Sieur de La Salle
Baron Joseph Maria Christoph von Lassberg
Classical Latin Literature in the Church
Diocese of Lausanne and Geneva
Pierre Gaultier de Varennes, Sieur de Lavérendrye
Charles-Martial-Allemand Lavigerie
Influence of the Church on Civil Law
Order of St. Lazarus of Jerusalem
Emile-Paul-Constant-Ange Le Camus
Ven. Louise de Marillac Le Gras
Diocese and Civil Province of Leon
Liber Diurnus Romanorum Pontificum
Ven. Francis Mary Paul Libermann
Bruno Franz Leopold Liebermann
Justin Timotheus Balthasar, Freiherr von Linde
Ancient Diocese and Monastery of Lindisfarne
Etienne-Charles de Loménie de Brienne
Francisco Antonio de Lorenzana
Pietro and Ambrogio Lorenzetti
Sisters of Loretto at the Foot of the Cross
St. Louis-Marie Grignion de Montfort
Brothers of Our Lady of Lourdes
Diocese of Luni-Sarzana-Brugnato
Jean-Baptiste-Alphonse Lusignan
Diocese of Lutzk, Zhitomir, and Kamenetz
Mathematician, astronomer, physicist, naturalist, and painter, b. in Paris, 18 March, 1640; d. in Paris, 21 April, 1718; was, as Fontenelle said, an academy in himself. His father, Laurent de La Hire, (1606-1656), was a distinguished artist. Philippe first studied painting in Rome, where he had gone for his health in 1660, but on his return to Paris, soon devoted himself to the classics and to science. He showed particular aptitude for mathematics, in which subject he was successively the pupil and associate in original investigation of Desargues. In 1678, he was made a member of the Academy of Sciences, section of astronomy. Beginning in 1679, in connexion with the construction of a map for the Government, he made extended observations in Brittany, Guienne, Calais, Dunkirk, and Provence. In 1683, he continued the principal meridian north from Paris, Cassini at the same time continuing it south, and, in 1684, he investigated the flow and fall of the River Eure in connexion with the water-supply of Versailles. His attainments won for him professorships both at the Collège de France, in 1682, and at the Academy of Architecture. Two of his sons rose to distinction, Gabriel-Philippe (1677-1719), in mathematics, and Jean-Nicolas (1685-1727) in botany. Industry, unselfishness, and piety were noteworthy traits of his character.
The chief contributions of La Hire were in the department of pure geometry. Although familiar with the analytic method of Descartes, which he followed in treatises published in 1679, his most important works were developed in the method of the ancients. He continued the work of Desargues and of Pascal and introduced into geometry, chiefly by a new method of generating conics in a plane, several conceptions related to those of recent times. In his exhaustive work on conics, published in 1685, he not only simplified and improved the demonstrations of many well-known theorems, but he also established several new ones, particularly some concerning the theory of poles and polars, a subject not fully developed until the nineteenth century. In this work appears for the first time the term "harmonic". Of the writings of La Hire which were, for the most part, published in the "Mémoirs" of the Academy of Sciences, and which treat of mathematics, astronomy, meteorology, and physics, the following are the most important: "Nouvelle Méthode en Géométrie pour les sections des superficies coniques et cylindriques" (1673); "Nouveaux Eléments des Sections Coniques: Les Lieux Géométriques: Les Constructions ou Effections des Equations" (in one vol., Paris, 1679); "Traité de Gnomonique" (1682); "Sectiones conicæ in novem libros distributæ" (Paris, 1685); "Tables du soleil et de la lune" (1687); "Ecole des arpenteurs" (1689); "Mémoire sur les conchoïdes" (1708); "Traité de mécanique" (Paris, 1729).
CHASLES, Aperçu historique sur l'origine et le développement des Méthodes en Géométrie (3rd ed., Paris, 1889); LEHMANN, De La Hire und seines Sectiones Conicæ, in supplement to Jahresbericht des königlichen Gymnasium zu Leipzig (Leipzig, 1888, 1890).
Paul H. Linehan.