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Leiden University archives, Observatory, directorate E.F. van de Sande Bakhuyzen

Identifier: ubl146

Scope and Contents

The archive consists of professional correspondence, correspondence and papers regarding the management of the Observatory, and papers regarding the maintenance of the scientific instruments and the building. It also includes papers regarding two international committees (International Time Conference and Fundamental Star Committee).

The papers also include correspondence by C. Sanders, who performed observations from Matuba in Portuguese Congo, Africa. Later letters from Sanders can be found in the W. de Sitter papers.


  • Creation: c. 1883-1918
  • Creation: Bulk c. 1908-1918


Language of Materials

Mostly Dutch, also German, French and English

Conditions Governing Use

Since the archive is digitized, the original papers are not free for public access, unless with permission of the curator after a written request with motivation. Other regulations that apply during the use of these materials can be found on the website of Leiden University Library.

Biographical / Historical

Ernst Frederik van de Sande Bakhuyzen (1848-1918) was appointed as observer at Leiden Observatory by his brother Hendrik, who was the director from 1872. He participated in the Venus transit expedition of 1874-75. In 1908 he succeeded his brother as director of the Observatory. He did not become professor of astronomy, as his brother had been; that position went to Willem de Sitter.

Like his brother, he worked mainly on the elimination of systematic errors from astronomical measurements. His directorate is generally considered to be a period of decline of the Observatory, in which hardly any scientific work was published.

Ernst van de Sande Bakhuyzen died unexpectedly in 1918. He was succeeded by Willem de Sitter.


100 items (c. 0.80 metre)

Abstract in Dutch

Archief afkomstig van E.F. van de Sande Bakhuyzen, observator en directeur van de Leidse Sterrewacht (1908-1918). Dit archief bestaat uit wetenschappelijke correspondentie en stukken betreffende het beheer van de Leidse Sterrewacht en het onderhoud van het gebouw en de instrumenten.

Abstract in English

Archive created by E.F. van de Sande Bakhuyzen, observer and director of Leiden Observatory (1908-1918). The archive consists of professional correspondence and papers regarding the management of Leiden Observatory and the maintenance of the building and instruments.


The inventory consists of the following categories:

Correspondence by correspondent (no. 1-52)
Correspondence by institution (no. 53-60)
Correspondence by subject (no. 61-72)
Committees, notes and observations (no. 73-86)
Observatory Management (no. 87-95)
Instruments (no. 96-100)

To facilitate researchers, each file has been given a short title. In some cases these titles were original designations by the authors. The other titles are given by the author of this inventory. The main subject of each file is indicated in the inventory. This is not an exhaustive description, but a first indication, intended for researchers.

Correspondence has been ordered alphabetically by correspondent, following the Dutch system (disregarding prefixes such as van, van der etc).

Within the files, correspondence has been ordered chronologically. Other papers are preserved in the order in which they were found.

"Correspondence with ..." indicates that the file contains letters from both correspondents; "letters from …" indicates that only one side of the correspondence has been preserved in this archive.

Physical Location

Leiden University Library, Special Collections

Custodial History

This archive was were created by Ernst van de Sande Bakhuyzen in the course of his work. The papers were preserved in Leiden Observatory until they were transferred to Leiden University Library in 2010.

Some files come from the collections of Museum Boerhaave. These files are indicated in the inventory.

Immediate Source of Acquisition

The archive was transferred to Leiden University Library in 2010, by agreement between Leiden Observatory, the Leiden University Library and the Department of Documentary Information and Archive Administration of Leiden University.


No selection has been made in this archive.


No future additions are to be expected.

Existence and Location of Copies

The archive is digitized. The images are available in the inventory.

Related Materials

This archive is part of Leiden Observatory Archives, which contain the papers of the Observatory and its directors from c. 1830-1945.

The collection of Leiden University Library also includes the scientific papers of Jan Oort (director of the Observatory from 1945-1970).

Separated Materials

Papers regarding the Venus transit expedition can be found in the H.G. van de Sande Bakhuyzen archive.


  • [Gent, R. van], De reizende astronoom. Nederlandse sterrenkundige expedities naar de Oost en de West (Leiden 1993).
  • Herk, G. van, H. Kleibrink en W. Bijleveld, De Leidse sterrewacht. Vier eeuwen wacht bij dag en nacht (Zwolle 1983).
  • Sitter, W. de, Short history of the observatory of the university at Leiden 1633-1933 (Haarlem 1933).

Processing Information

The archive has been reordered and repacked. Most of the folders were created by Bakhuyzen himself. The original files were maintained as much as possible. Correspondence has been ordered chronologically.

Collection guide of the Leiden University archives, Observatory, directorate E.F. van de Sande Bakhuyzen (c. 1883-1918)
Archieven van de Universiteit Leiden - Sterrenwacht, directoraat E.F. van de Sande Bakhuyzen
David Baneke, 2010
Language of description
Script of description
Code for undetermined script
Language of description note
Beschrijving is in het Engels.

Revision Statements

  • 10 September 2015: latest update

Repository Details

Part of the Leiden University Libraries Archives & Collections Repository

Witte Singel 27
Leiden 2311 BG Netherlands
+31 71 527 2857