The Kenya Expeditions of Leiden Observatory

Three major sources of material have been used for the present article, namely: (1) the correspondence between C. Sanders and E. van de Sande Bakhuysen and between C. Sanders and W. de Sitter, from the archives of Leiden Observatory, (2) the files on the Kenya expeditions archived with the Oort Papers, at the Leiden University Library, department of Western Manuscripts, and (3) an interview with G. van Herk (who participated in both expeditions), which has been recorded on tape. The first source comprises boxes 4 (files 8–16), 20 (file 17) and 122A of the Observatory archives, the second source comprises boxes of which the number starts with 3.7 within the Oort Papers. Within the references these sources are referred to as S + number, O + number and “G. van Herk, private communication” respectively.

Kapteyn J.C. , “Ueber eine Methode die Polhöhe zu bestimmen”, Copernicus , iii (1883), 147–82.

Sanders C. to Van de Sande Bakhuyzen E. , 18 January 1917 (in English), S4.8.

Sanders C. , “Determination of latitude and declinations”, The observatory , xl (1917), 271–3.

Ibid. , 273.

De Sitter W. Oort J. H. , “A provisional scheme for the determination of fundamental declinations from azimuth observations”, Bulletin of the Astronomical Institutes of the Netherlands , iii (1925), 1–6.

Sanders C. Oort J. H. , “A discussion of the determination of declinations from azimuth measures made near the equator”, ibid. , ii (1925), 201–8.

W. de Sitter to the Director of Quito Observatory, G. Tufino, 26 June 1929 (in English), O3.7.1931(b).

Letter from Perrier G. , previous director of Quito Observatory, 30 January 1930 (in English), O3.7.1931(b).

As repeatedly reported by De Sitter in letters to C. H. Hins, see O3.7.1931(a).

Letter from Hins C. H. de Sitter W. , late 1931 (original in Dutch), O3.7.1931(a).

Records of Hins C. H. , 22 October 1931 (original in Dutch), O3.7.1931(a).

Letter, Hins C. H. Oort J. H. , 1 January 1932 (original in Dutch), O3.7.1931(a).

Hins does not seem to have considered at this stage that the deviation might reflect a local deflection of the vertical, as might well have been the case (G. van Herk, private communication).

Letter, Hins C. H. de Sitter W. , 22 March 1932 (original in Dutch), O3.7.1931(a).

Quoted by De Sitter in a letter to Hins, 22 August 1932 (original in Dutch), O3.7.1931(a).

Quoted by De Sitter in a letter to Hins, 25 June 1932 (original in Dutch), O3.7.1931(a).

Letter, Sanders C. van de Sande Bakhuyzen E. , 27 May 1918 (in English), S122.

Letter from Hins C. H. de Sitter W. , early May 1932 (original in Dutch), O3.7.1931(a).

Letter from Hins C. H. de Sitter W. , 27 October 1932 (original in Dutch), O3.7.1931(a).

This was an optimistic estimate. Temperatures actually did fall to near the freezing point (G. van Herk, private communication).

Van Herk tells of having to avoid a herd of wild boars on another occasion when going to the observing hut on foot (G. van Herk, private communication).

Hins's records, 22 October 1931 (original in Dutch), O3.7.1931(a).

Letter from Hins C. H. de Sitter W. , 20 February 1933 (original in Dutch), O3.7.1931(a).

Hins C. H. Van Herk G. , “A catalogue of fundamental declinations derived from azimuth observations at a station on the Earth's equator”. Annalen van de Slerrewacht te Leiden , xviii/1 (1938).

Minute of letter from Oort J. H. Van Rhijn P. J. , 29 January 1943 (original in Dutch), O2.2.1944(d).

Letter from Department of Education to Observatory, Leiden, 25 October 1947 (original in Dutch), O3.7.1946(g).

Answer to above, 31 October 1947 (original in Dutch), O3.7.1946(g).

Letter from Odermatt J. to Oort J. H. , 30 December 1946 (in English), O3.7.1946(g).

Article submitted to Elsevier's Weekblad by van Zadelhoff W. in 1949, O3.7.1948.

According to Van Herk this cannot have been very wet in view of the usual shortage of water (G. van Herk, private communication).

Van Herk G. , “Absolute declinations of 1493 stars from azimuth observations”. Annals of Leiden Observatory , xviii/5 (1957), 11.

Ibid., passim. .

Ibid. .

Evans David S. , Under Capricorn (Bristol, 1988), 160.