Henricus Gerardus (Hendrik) van de Sande Bakhuyzen was born in The Hague on 2 April 1938, as son of a prominent painter of the same name. He studied civil engineering at the Delft Polytechnic before turning to astronomy. In 1863, he obtained his doctorate at Leiden University, supervised by Frederik Kaiser, professor of astronomy and founder of a modern new observatory in Leiden. For several years after, Bakhuyzen worked as a teacher and later as a professor of applied physics in Delft, before succeeding Kaiser in Leiden in 1872. He remained there until his retirement in 1908, when he was succeeded by his younger brother Ernst (1848-1918).

Bakhuyzen continued Kaiser’s work on fundamental astrometry: high-precision measurement of star positions using a meridian telescope. Most of his work concerned investigating systematic errors in the measurements, both instrumental and personal. He also conducted high-precision research in other fields, such as atmospheric refraction and the rotation of Mars. Finally, he worked on geodesy, including longitude measurements and sea level determinations. This led, among other things, to a correction of all the longitudes of European observatories in 1894.

Later generations of astronomers have described Leiden Observatory during Bakhuyzen’s directorship as a period of stagnation and decline. His obsession with precision led to long delays in the publication of measurements. After a new 13-inch photographic refractor was installed in Leiden in 1898, no observations made with the new instrument were published by the time the younger Bakhuyzen retired twenty years later: the staff was still working on its systematic errors.

Bakhuyzen was active in many national and international scientific organizations. For example, he was president of the Science Section of the Royal Netherlands Academy of Sciences from 1888-1909 and vice president of the (German) Astronomische Gesellschaft from 1889-1896. From 1900 he was secretary of the International Geodetic Association. He was also a member of the committee that coordinated the international Carte du Ciel project, a program to photograph the entire sky and measure the positions of millions of stars. Characteristically, Bakhuyzen’s own contribution involved investigating the systematic errors on the photographic plates. The Carte du Ciel project was long regarded as a white elephant, but recent developments (such as the Hipparcos astronometry project) have given it a new lease of life.

Hendrik van de Sande Bakhuyzen retired in 1908; he died in 1923.

Several publications by Van de Sande Bakhuyzen are available online.

The album was presented to Bakhuyzen by H.A. Lorentz, physics professor in Leiden, on 8 November 1908. For a long time, the album was preserved at Leiden Observatory. In 2010 it was transferred to the Leiden University Library, together with the archives of Leiden Observatory. These archives cover the period from c.1835-1950, including the scientific papers of Bakhuyzen, his predecessor Frederik Kaiser, and his successors Willem de Sitter and Ejnar Hertzsprung. The papers of Jan Oort had already been transferred earlier. The archives were digitized and the album was restored. This was sponsored by the Metamorfoze-program for the preservation of papers belonging to the national heritage and the Gratama Foundation. Now the observatory archives are part of the Special Collections of the library. Due to its fragility, the original album is not available for viewing, unless with special permission of the curator.

The album is a large book with a sheep’s leather cover and metal locks. It is literally too large and heavy to handle, which has caused the cover to be damaged several times in the past. After the title page and a painting of Leiden Observatory, the album opens with a series of photos of Leiden Observatory and its staff. Bakhuyzen himself is not included; only his brother E.F. (Ernst) van de Sande Bakhuyzen, who succeeded him as director. Leiden is followed by the other astronomical institutions of the Netherlands. The next pages show a large number of Dutch scientists and scholars, including famous people such as Lorentz and Kamerlingh Onnes. The next part of the album shows astronomical institutions from around the world, starting with Kazan in Russia. The pictures show buildings, telescopes and scientists from many nations, including most European countries but also South Africa, the United States, Mexico, Argentina and Australia. It features well-known scientists such as Max Planck, George Ellery Hale and Norman Lockyer, but also many lesser known figures. The last few pages contain photos that apparently arrived too late to be included in the main body of the book, including two of Japanese scientists.

References to the album should mention Leiden University Library, Leiden Observatory Archives.

Links to the album on the Leiden University Library webpage:

Online presentation
High Resolution Viewer

The title page is a parchment sheet with painted miniatures. The text reads: “To Henricus Gerardus van de Sande Bakhuyzen at the occasion of his retirement as Professor of Astronomy at the State University of Leiden on 21 September 1908, in thankful appreciation of his services to science and the nation.” At the bottom of the page is the Academy building of Leiden University. The coats of arms represent the cities of The Hague and Leiden and the Leiden Student Corps ‘Minerva’.

The painting of Leiden Observatory that follows the Album's title page was made by Julius van de Sande Bakhuyzen (1835-1925), a brother of Hendrik. He was a relatively well-known painter from the Haagse School, a group of painters from The Hague in the late nineteenth century. The Bakhuyzen family included several professional painters, most notably Hendrik and Julius’ father Hendrik van de Sande Bakhuyzen (1795-1860). The quote on the page is from Vergil’s Aeneid: “He observes every star in the gliding sky” (Aeneid III 515).

D. Baneke, ‘Een fotoalbum van formaat’, Zenit, July/August 2010, 321-327.
G. van Herk, H. Kleibrink and W. Bijleveld, De Leidse Sterrewacht: Vier eeuwen wacht bij dag en nacht (Zwolle 1983).
T. de Liefde-van Brakel, Hendrikus, Gerardine en Julius van de Sande Bakhuyzen: Een Haagse schildersfamilie uit de negentiende eeuw (Zwolle 1997).
F. van Lunteren, ‘Hendricus Gerardus van de Sande Bakhuyzen’, in Th. Hockey et al. (eds.), The Biographical Encyclopedia of Astronomers (Springer 2007).
W. de Sitter, ‘Hendrik Gerard van de Sande Bakhuyzen’, Monthly Notices of the Royal Astronomical Society 84 (1924) 226-230.

The photo of H.G. van de Sande Bakhuyzen on this page is used with kind permission of the Academisch Historisch Museum Leiden.