SCHWABE, SAMUEL HEINRICH

(b. Dessau, Germany, 25 October 1789; d. Dessau, 11 April 1875)

astronomy.

Schwabe’s father was a physician, and the family apothecary business was derived from his mother’s family. After working from 1806 to 1809 as an assistant in the business, Schwabe continued his pharmaceutical studies at the University of Berlin in 1810–1812, under Klaproth and Hermbstädt While at Berlin he became interested in astronomy and botany. Schwabe worked as an apothecary from 1812 until 1829, when he sold the business in order to give his time fully to his scientific interests.

On 17 December 1827 Schwabe rediscovered the eccentricity of Saturn’s rings. In 1843 he made his first definite statement regarding the periodicity of sunspots, giving statistics for 1826–1843. He tabulated his results under four headings: the year, the number of groups of sunspots in the year, the number of days free from sunspots, and the number of days when observations were made. Schwabe realized that with the modest apparatus in his private observatory, numerical determination was difficult: for instance, on days when there was a large number of spots, he had probably underestimated them. His carefully compiled results demonstrated the existence of periodicity, although he wrongly estimated the period to be about ten years. His discovery remained unnoticed until Humboldt drew attention to it in 1851. Because Schwabe was an amateur astronomer, his discovery was all the more noteworthy, for the investigation of the occurrence of sunspots had been judged unprofitable by Lalande and Delambre.

After Schwabe’s discovery, Rudolf Wolf collated all existing sunspot data and recalculated the period as just over eleven years. In 1857 the Royal Astronomical Society awarded Schwabe its gold medal. He was elected a member of the Royal Society of London in 1868.

BIBLIOGRAPHY

I. Original Works. The Royal Society Catalogue of Scientific Papers, V, 582–585: and VIII, 901, lists 109 of Schwabe’s printed papers and scientific works, including papers on the phenomena of frost patterns, haze, and mock suns. In 1865 he published a flora of Anhalt. Thirty-one volumes of Schwabe’s astronomical observations were transferred after his death into the keeping of the Royal Astronomical Society. They cover his work from 1825 to 1867 and are held in the Society archives at Burlington House, London. See also Poggendorff, II 871:III, 1223; VI, 2391.

II. Secondary Literature. Biographical information is in Allgemeine deutsche Biographic, XXXIII, 159–161; T. Arendt, Schwabe: Leben und Wirken (Dessau, 1925), which I have not been able to see: and Gustav Partheil, “Samuel Heinrich Schwabe der dessauer Astronom und Botaniker,” in Jahrbuch, Heimatliches, für Anhalt 1926. Accounts of his work appear in Alexander von Humboldt, Kosmos: Entwurfeiner physischen weltbescheibung, III (Stuttgart-Augsburg, 1851), 379–405; and H. H. Turner, Astronomical Discovery (London, 1904), 155–176.

Sister Maureen Farrell, F.C.J.