Untersuchungen über die Lange des einfachen Secundenpendels

Berlin: Kgl. Akademie der Wissen. zu Berlin, 1828. OFFPRINT. Recent half leather over marbled boards.. A very good copy with some light spotting.. 4to, [6], [1] - 254, [2 - original blank] pp. + 2 engraved plates of the apparatus.

One of the important geophysical works undertaken by Bessel. The text describes the construction (in conjunction with the famous maker Repsold) and painstaking design of the instrument to achieve the high standard of accuracy demanded for precise astronomical calculations. The second pendulum clock of the observatory was not meant to provide information about the time but to indicate the regular rotation of the celestial sphere for star mapping. Errors and inaccuracies played havoc with the measurement of the right ascension. Bessel's accomplishment was to produce a device of great accuracy and mathematical precision. Bessel offered his paper for publication in 1828. At that time the Proceedings of the Berlin Academy were two years behind in their publication dates. Bessel's work, however, was deemed to be of such importance that the editors chose to break the proper chronological entry and publish this lengthy work as part of the Proceedings then in press, i.e., the year 1826. The prefatory statement explaining this is present only in the offprint offered here. The entry in Poggendorff and the DSB for 1826 is therefore an understandable error. One of the best accounts of Bessel's device and its construction is in Lenzen and Multhauf's work on the development of gravity pendulums. DSB I, 97-102; see Lenzen & Multhauf.