Adolf Repsold was a prominent German astronomer and mathematician who was a famous instrument maker. He is noted for designing a heliometer for Oxford (1842), improving the design of the pump used in firefighting operations, and for completion of the Oxford heliometer in 1849.
Background
Adolf Repsold was born on August 31, 1806, in Hamburg, Germany. His family name derives from that of a manor house, Hrepesholt, in East Friesland, which is first recorded in connection with the establishment of a monastery in 983. In Johann Georg, Adolf, and Johann Adolf Repsold, the family produced three generations of outstanding designers and builders of astronomical instruments. The first of these, Johann Georg Repsold, was the third child and eldest son of a minister and was himself intended for a career in theology.
Career
Adolf Repsold succeeded his father Johann Georg Repsold as a fire captain and then served an apprenticeship in his father’s workshop and, with his brother Georg, assumed direction of the family instrument business, renamed A. and G. Repsold. Adolf Repsold’s first commissions were for a small transit instrument for Bessel and for a similar nine-foot (2.74-meter) instrument for the Edinburgh observatory, which was installed in 1831, the same year in which Repsold also designed a lamp system for the lighthouse on Wangerooge Island.
In 1833 and 1834 he received orders for meridian circles for the Hamburg and Pulkovo observatories that obliged him to complete the large circular dividing machine that his father had begun. In 1838 he completed a transit instrument for use in the first vertical circle at Pulkovo; it was made to an innovative design whereby a system of levers was employed to compensate for axial deflection.
In 1836 Karl August von Steinheil came to Hamburg from Munich to assist Adolf Repsold in the manufacture of several standard measuring devices, including a rock-crystal kilogram weight and a glass meterstick, that had been ordered by the Bavarian state government. Steinheil contributed directly to one of the two great innovations that Repsold made during the 1840’s - the cylindrical manipulation of the split objective and the apparatus by which scales could be read directly from the objective. It was Steinheil’s suggestion that the scales, in the latter instance, be illuminated by means of electrically activated glowing platinum wires, a proposal that resulted in the practical application of the platinum-coil vacuum incandescent lamp that W. R. Grove had invented in 1840. Repsold may have also made use of a technique, patented by Frederick de Moleyns in 1841, to increase the brightness of the platinum coil by the injection of powdered charcoal.
Adolf Repsold also received constant help and encouragement from Bessel, who visited him in 1839 and ordered a meridian circle for the Konigsberg observatory, which was installed in 1841, the same year in which Repsold completed an equatorial instrument with a clockwork mechanism for the Christiania (now Oslo) observatory. The latter instrument was novel not only in that it compensated for deviations in the axis of declination by a system of weights, but also in that it incorporated a fine adjustment, which was entirely independent of the clockwork, for the right ascension and a microscopic circular reading dial.
In 1842 Adolf Repsold was engaged in designing a heliometer for Oxford, a project in which he was particularly interested when his work was interrupted by the great Hamburg fire of that year.
He was stimulated to improve the design of the pump used in firefighting operations and developed a vibrationless vane model that reduced the danger of breaking through the ice of the harbor during the winter months. Although Repsold’s vane pump had only a single cog for each wheel, it was more powerful than the rotating reciprocating engine employed until that time. In 1849 he completed the Oxford heliometer.
Adolf Repsold built a new workshop in 1855, in which he manufactured an eight-foot (2.44-meter) refracting telescope for the observatory at Lisbon and an equatorial instrument for the Gotha observatory.
From 1859 he was assisted by his eldest son, Johann Adolf Repsold, who had served an apprenticeship in the family laboratory, then worked for a year with C. A. F. Peters at the Altona observatory. In 1862 Johann Adolf Repsold became a partner in the family business; in 1867 another of Adolf Repsold’s sons, Oskar, also joined the firm, and its name was changed again, to A. Repsold and Sons. Adolf Repsold simultaneously continued to work in the fire department, and in 1856 was promoted to Oberspritzenmeister, the post formerly held by his father.
In 1858 he was made a head of the central office of the Hamburg fire department and worked toward increasing its effectiveness until his death from a heart attack in 1871.