Louis Joblot and his microscopes.

Abstract

Louis Joblot was born in 1645 in Bar-le-Duc, a small town located where Lorraine and Champagne meet in the picturesque valley of Ornain. He died in Paris in 1723. During his life, Joblot was engaged primarily in the study of physics: magnetism and optics had a special fascination for him. It is mainly because of his microscopes and what he saw with them that we remember him. Louis Joblot was a contemporary of Antony van Leeuwenhoek, both men dying in the same year. The details of the life of Joblot have been poorly documented, and what little we know was religiously assembled by a certain Wlodimir Konarski who buried his work in an obscure journal, published in 1895, dedicated to the local history of Joblot's native town, Bar-leDuc (12). Louis Joblot was baptized on August 9, 1645. His parents were probably local merchants of some wealth. How and when he found his way to Paris is not known, but in 1680, he was appointed assistant to the well-known engraver Sebastien Le Clerc (1637-1714) to teach geometry to the students of the Royal Academy of Painting and Sculpture. This position carried no salary, and we must assume that Joblot was either independently wealthy or had some other source of income, possibly from giving private lessons in mathematics. In 1697, he requested a leave of absence of 15 to 18 months to travel in Italy, the cradle ofthe arts. In 1699, he was appointed Professor of Perspective and Geometry, replacing Le Clerc. In his lectures, he stressed the mechanism of vision and even indulged in the dissection of eyes. He was then entitled to a salary of 300 pounds a year, which was less than that paid by the Academy to a model! In 1717, it was his turn to request the appointment of an assistant, and four years later he retired, retaining the title of Counselor and Professor Emeritus. He died on April 27, 1723. This is the extent of the hard facts that we have concerning the life of Joblot. To this we might add that he was probably not married, that he associated with those interested in science, delighting them with experiments and demonstrations in the field of magnetism and microscopy, and that he lived in that part of Paris where makers of precision instruments were concentrated. Joblot interests us because of a book that he published in 1718, which was entitled Descriptions and Uses of Several New Microscopes, Both Simple and Compound (Descriptions et Usages de Plusieurs Nouveaux Microscopes tant Simples que Composez). Part of it was translated into English by Adams in 1746 (1). Joblot's book was republished in 1754 and 1755 in two volumes entitled Natural History Observations Made with the Microscope (Observations d'Histoire Naturelle Faites avec le Microscope). The publisher, Briasson, had bought the plates of Joblot's book and had added some material of little importance, mainly on insects, to the original text in order to make a "new book." For obvious reasons, the second edition of Joblot's book never received the author's blessing and was simply a device to make money for M. Briasson. Jean Senebier (14) of Geneva refers to Joblot's book in the introduction to his 1787 French translation of Spallanzani's Opuscoli di Fisica Animale e Vegetabile. After that, Dujardin (1841) (9) wrote: "Joblot, in 1754, published microscopic observations which were rather good for the time, and which are not without value, in spite of the ridiculous names used...." Dujardin did not seem to be aware of the fact that the 1754 edition was only, as far as microbiology is concerned, a reproduction of the 1718 edition. If Joblot's observations were good for 1754, they must have been outstanding for 1718! Dujardin's error was pointed out by Fleck in 1876 (10). In 1894, Cazeneuve (5) explained how he had read the 1754 French translation of Henry