1842 births

Wilhelm Emil Fein (16 January 1842 – 6 October 1898) was a German inventor. He invented the worldwide first portable electric drill.

Johann Friedrich Wilhelm Camerer (17 October 1842 – 25 March 1910) was a German physician born in Stuttgart. Camerer was a pioneer in the field of pediatric medicine.He studied medicine at the universities of Tübingen and Vienna. At Tübingen he was a student of physiologist Karl von Vierordt (1818–1884). From 1867 to 1876 he was a general practitioner in several communities throughout Württemberg, afterwards working as a physician in the town of Riedlingen (1876–1884). During the Austro-Prussian War (1866) and Franco-Prussian War (1870–71), he served as a military physician.
From 1884 onward, he was a physician based in Urach, where he was later appointed Oberamtsarzt (medical officer). In 1895 he received an honorary degree in natural sciences from the University of Tübingen.
Camerer is remembered for his studies of infant nutrition and psychophysics as well as research involving metabolism in children. In 1894 he published an influential work on childhood metabolism called "Der Stoffwechsel des Kindes", etc. His work in pediatrics included important research on the composition of breast milk.

Jean Baptiste Paulin Trolard (27 November 1842 in Sedan, Ardennes – 13 April 1910) was an anatomist known for his work on the anastomotic veins of the cerebral circulation. The "vein of Trolard" (the superior anastomotic vein) was named after him.He studied medicine at the Algiers Preparatory College of Medicine, afterwards working as a municipal physician in Saint Eugène, a suburb of Algiers. In 1861, he began work as an anatomy prosector at the college. From 1869 to 1910, he was a professor of anatomy at the Mustapha Pacha hospital Algiers.Known for his work against contagious diseases and epidemics, he was a proponent of free vaccinations for all indigent peoples. In 1882, he founded La Ligue de Reboisement in an effort to promote reforestation and prevent the deforestation of Algeria for the sake of creating pastureland. With Henri Soulié, he was co-founder of the Pasteur Institute of Algeria in 1894.

Alphonse Francois Renard (27 September 1842 – 9 July 1903), Belgian geologist and petrographer, was born at Ronse, in East Flanders, on 27 September 1842. He was educated for the church of Rome, and from 1866 to 1869 he was superintendent at the college de la Paix, Namur.In 1870 he entered the Jesuit Training College at the old abbey of Maria Laach in the Eifel, and there, while engaged in studying philosophy and science, he became interested in the geology of the district, and especially in the volcanic rocks. Thenceforth he worked at chemistry and mineralogy, and qualified himself for those petrographical researches for which he was distinguished.In 1874 he became professor of chemistry and geology in the college of the Belgian Jesuits at Leuven, a few years later he was appointed one of the curators of the Royal Natural History Museum at Brussels, and in 1882 he relinquished his post at Louvain. In 1888 he was chosen professor of geology at the University of Ghent, and retained the post until the close of his life. Meanwhile, he had been ordained priest in 1877, and had intended to enter the Society of Jesus. He was known as the Abbé Renard; but, as remarked by Sir A. Geikie, as years passed, the longing for mental freedom grew ever stronger, until at last it overmastered all the traditions and associations of a lifetime, and he finally separated himself from the church of Rome.His first work, written in conjunction with Charles-Louis-Joseph-Xavier de la Vallée-Poussin (1827–1904), was the Mémoire sur les caractères minéralogiques et stratigraphiques des roches dues plutoniennes de la Belgique et de l'Ardenne française (1876). In later essays and papers he dealt with the structure and mineral composition of many igneous and sedimentary rocks, and with the phenomena of metamorphism in Belgium and other countries. In acknowledgment of his work, the Bigsby Medal was awarded to him in 1885 by the Geological Society of London. Still more important were his later researches connected with the Challenger Expedition. The various rock specimens and oceanic deposits were submitted to him for examination in association with Sir John Murray, and their detailed observations were embodied in the Report on the Scientific Results of the Voyage of H.M.S. Challenger Deep Sea Deposits (1891). The more striking additions to our knowledge included the detection and description of cosmic dust, which as fine rain slowly accumulates on the ocean floor; the development of zeolitic crystals on the sea-bottom at temperatures of 32 °F (0 °C) and under; and the distribution and mode of occurrence of manganese nodules and of phosphatic and glauconite deposits on the bed of the ocean. Renard died at Brussels on 9 July 1903.Rue Alphonse Renard, in western Ixelles, is named in his honor. In addition, the mineral renardite was named in his honor in 1928.

Siegmund Mayer (December 27, 1842 – September, 1910) was a German physiologist and histologist.
Mayer was born in Bechtheim in Rhenish Hesse. He studied at the Universities of Heidelberg, Giessen and Tübingen, where in 1865 he obtained his doctorate. He subsequently worked with Hermann Ludwig Ferdinand von Helmholtz (1821–1894) in Heidelberg, Carl Friedrich Wilhelm Ludwig (1816–1895) and Julius Friedrich Cohnheim (1839–1884) in Leipzig, and with Ernst Wilhelm von Brücke (1819–1892) in Vienna.
In 1869 he was habilitated for physiology at Vienna, and during the next year became Karl Ewald Konstantin Hering's assistant in Prague. In 1872 he became an associate professor and in 1887 a full professor. From 1880 he was director at the newly founded institute of histology.
Mayer made several important contributions particularly concerning the physiology of the heart and vessels, respiration and intestines. He was one of the first to describe chromaffin cells in the sympathetic nerve, and with Ewald Hering and Ludwig Traube, his name is associated with "Traube–Hering–Mayer waves", a phenomenon that deals with rhythmic variations in arterial blood pressure.In addition to his scholarly papers published in scientific journals, he made contributions to Salomon Stricker's Handbuch der Lehre von den Geweben des Menschen und der Thiere (1872) and to Ludimar Hermann's Handbuch der Physiologie (1879). He was also author of Histologisches Taschenbuch (1887).
Mayer died September 1910 in Prague.

François Émile Maupas (2 July 1842 in Vaudry – 18 October 1916 in Algiers) was a French librarian, protozoologist, cytologist, and botanist. Maupas contributed to ideas on the life cycle and reproduction of the ciliates. He founded the idea, known as the Maupasian life cycle, that some protists had a definite death following sexual reproduction, contrary to contemporary ideas on protists being immortal. He also identified the existence of mating types in ciliates. He developed culture techniques for a number of organisms and described the nematode Caenorhabditis elegans, which has since become a widely used model organism in biological studies.

Hermann Friedrich Lossen (7 November 1842 – 27 August 1909) was a German surgeon born in Emmershäuser Hütte, Hesse.
He studied under Carl von Voit (Munich), Friedrich Daniel von Recklinghausen (Würzburg), Bernhard von Langenbeck (Berlin) and Theodor Billroth (Vienna), earning his medical doctorate in 1866 from the University of Würzburg. In addition he served as an assistant to Richard von Volkmann at the University of Halle and to Gustav Simon at the University of Heidelberg. In 1866 he became habilitated for surgery at Heidelberg, where in 1874 he was appointed associate professor.

Carl (or Karl) Otto Harz (28 November 1842 in Gammertingen – 5 December 1906 in Munich) was a German mycologist, pharmacist and botanist.
After spending time as an intern in several pharmacies, he studied botany at the University of Berlin. Later, he relocated to Munich, where he served as a lecturer at the Technische Universität München (from 1873) and at the Tierärztlichen Hochschule (from 1874). In 1880 he was appointed professor of botany and pharmacognosy at the Tierärztlichen Hochschule.In 1877, with pathologist Otto Bollinger, he conducted early studies of actinomycosis in cattle, and is credited for naming the causal agent Actinomyces bovis. From his observations, he believed the culprit to be a mould, related to the genera Botrytis or Monosporium.As a taxonomist, he circumscribed a number of varieties from the species Cucurbita pepo. His name is associated with the following mycological genera:

Harzia (family Ceratostomataceae), named by Julien Noël Costantin (1888).
Harziella (family Chaetomiaceae), named by Otto Kuntze (1891).

François Henri Hallopeau (17 January 1842, Paris – 20 March 1919, Paris) was a French dermatologist. He studied medicine under Alfred Vulpian and Sigismond Jaccoud. He co-founded and was secretary general of the Société Française de dermatologie et de syphiligraphie. He became a member of the Académie de Médecine in 1893.
He coined the medical term trichotillomania in 1889. He also coined the word antibiotique in 1871 to describe a substance opposed to the development of life.Selman Waksman was later credited with coining the word antibiotic to describe such compounds that were derived from other living organisms, such as penicillin.

Joseph Valentin Boussinesq (pronounced [ʒɔzɛf valɑ̃tɛ̃ businɛsk]; 13 March 1842 – 19 February 1929) was a French mathematician and physicist who made significant contributions to the theory of hydrodynamics, vibration, light, and heat.