NOBERT, FRIEDRICH ADOLPH

(b. Barth, Pomerania [now German Democratic Republic], 17 January 1806; d. Barth, 21 February 1881)

clockmaking, optical instruments.

Nobert was the elder son of Johann Friedrich Nobert, a clockmaker. After a scanty education he took up his father’s occupation. In 1827, at a Berlin trade exhibition, Nobert entered a pocket chronometer that was commended and brought him to the attention of the astronomer Johann Encke. To check the going of his timepieces Nobert constructed a telescope and, with Encke’s encouragement, made a number of astronomical measurements. In the spring of 1833, realizing that his ambitions would never be achieved without further education, he applied for a scholarship to study at the Technical Institute at Charlottenburg in Berlin. During the academic year 1833–1834 Nobert learned dividing methods and made a circle-dividing engine. This was most probably the machine with which he later ruled diffraction gratings, test objects, and micrometers; marked out scales for optical instruments; and cut chronometer gears. In 1835 Nobert was appointed Universitätsmechaniker at the University of Greifswald. During the 1840’s he began to develop the fine ruling techniques that brought him some measure of fame. Not long after his father’s death in 1846 Nobert returned to the family house in Barth, where he remained, working alone, until his death.

The key to Nobert’s production of scientific instruments is his use of the circle-dividing engine. The art of dividing straight lines, arcs, and circles into various numbers of equal parts is the most important and difficult aspect of the work of the mathematical instruments in dividing the circle (1845), Nobert described his newly discovered technique for using the dividing engine in ruling parallel lines on glass that was to be used in micrometers by microscopists. In 1846 he described an extension of the technique to the production of a resolution test plate for the microscope. At this time the optical microscope was undergoing rapid improvements in the design of the objective lens systems, and a standard physical test was needed for judging improvements in resolution. Nobert’s first test plate consisted of ten bands, each comprising a number of lines a definite distance apart, the first and tenth bands being ruled to a spacing of 2.25 and 0.56 microns respectively. Whenever the finest band on one of the test plates had been resolved by improved objectives, Nobert made another plate containing even finer bands; in all he made a series of seven different test plates between 1845 and 1873. The last plate in the series contained bands ruled to a spacing of 0.11 micron, well below the resolution limit of the optical microscope. Plates of this type were sold in London in 1880 for £15 apiece.

Nobert used his circle-dividing engine to produce rulings on glass for other purposes. The most important of these were the diffraction gratings made for V. S. M. van der Willigen in Haarlem and Ångström in Uppsala. For his celebrated measurements of the wavelengths of the elements in the spectrum of the sun, Ångström used four gratings made by Nobert. Other devices made by ruling were a micrometer for the astronomical telescope and a “spectrum plate” designed to prove that the velocity of light is greater in air than in glass. Nobert also made compound microscopes and objective lenses.

BIBLIOGRAPHY

1. Original Works. Nobert’s writings include “Ueber Kreistheilung im Allegemeinen und über einige, bei einer Kreislheilmaschine angewendete, verfahren zur Erzielung einer grossen Vollkommenheit der Theilung derselben,” in Verhandlungen des Vereins zur Beförderung des Gewerbfleisses in Preussen (1845), 202–212; “Ueber die Prüfung und Vollkommenheit unserer jetzigen Mikroskope,” in Annalen der Physik und Chemie 67 (1846), 173–185; “Ueber Glas-Skalen von Herren Universitats-Mechanicus Nobert in Greifwalde,” in Ergänzungs-Heft zu den Astronomischen Nachrichten (Altona, 1849), cols. 93–96; “Uber eine Glasplatte mit Theilungen zur Bestimmung der Wellenlange und relativen Geschwindigkeit des Lichts in der Luft im Glase,” in Annalen der Physik und Chemie, 85 (1852), 83–92; “Ein Ocularmikrometer mit leuchtenden farbigen Linien im dunkel Gesichtsfelde,” ibid., 93–97; “Die höchste Leistung des heutigen Mikroskops, und seine Prüfung durch künstliche und nutürliche Objekte,” in Mitheilungen aus dem naturwissenschaftlichen Vereine von Neu-Vorpommern und Rügell in Greifswald, 13 (1882), 92–105. For a list of papers on astronomical observations and other matters see the Royal Society’s Catalogue of Scientific Papers, IV, 628.

Some letters from Nobert to Ernst Abbe, as well as two microscopes made by Nobert, are in the optical museum of VEB Carl Zeiss, Jena. German Democratic Republic. Nobert’s circle-dividing engine is preserved in the Smithsonian Institution, Washington, D.C.

II.Secondary Literature. See W. Rollman, “Friedrich Adolph Nobert,” in Mittheilungen aus dem naturwissen schaftlichen Vereine von Neu-Vorpommern und Rügen in Greifswald, 15 (1884), 38–58; G. L’E. Turner, “The Microscope as a Technical Frontier in Science,” in Historical Aspects of Microscopy, S. Bradbury and G. L’E. Turner, eds. (Cambridge,1967), 175–199; “The Contributions to Science of Friedrich Adolph Nobert,” in Bulletin of the Institute of Physics and the Physical Society, 18 (1967), 338–348; and “F. A. Nobert’s Invention of Artificial Resolution Tests for the Optical Microscope,” in Actes du XI’ Congrès international d’histoire des sciences, III (Warsaw, 1968), 435–440; and G. L’ E. Turner and S. Bradury, “An Electron Microscopical Examination of Nobert’s Finest Test-Plate of Twenty Bands,” in Journal of the Royal Microscopical Society, 85,(1966), 435–447.

G.L’E.Turner