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Redegørelse vedrørende Urania-objektivet
Af Diplom-Astronom Hans G. Beck, Jena.
The story of the free gift of glass disks by Otto Schott to [Victor] Nielsen can be explained easily: When Scott started his work in Jena at the Glass Laboratories in 1884 he worked out a program to examine all possible varieties of combination of minerals. He executed a great number of tests, hundreds and hundreds. Because of the small sizes of the micro[scope] optics and the requirement for a prism to check the dispersion properties, the amount of glass for each test was not high.
However, it is recorded that Ernst Abbé, who was very much familiar with the work of Fraunhofer, proposed to Schott to smelt larger quantities for glasses that might be used for telescope optics. He suggested further to pour the glass fluid into a "form" of a cylindrical disk instead of a block of glass. By doing this Scott must have made a number of glass disks, but nobody in Jena had special experience in grinding and polishing larger sizes of lenses with high accuracy.
Ernst Abbé sent in 1866 his assistant Cars Czapski to Carl Bamberg, who was an apprentice of Carl Zeiss, and who made astronomical equipment in a workshop in Friedenau near Berlin. Czapski calculated two objectives, that were made at Bambergs workshop. But the glasses used, phosphorcrown and baratflint, were sensitive to the influence of the atmosphere. At that time Max Pauly used the new Jena glasses before he joined Zeiss in 1897.
Thus it is explained why the mounting of the lens shows no number. There is a further objective by Max Pauly in Frankfurt a. Main at the observatory of the Physikalischer Verein.