Erwin Finlay-Freundlich, Dr. Phil. (Göttingen), M.A., F.R.A.S.

by H von Klüjber

Professor Erwin Finlay-Freundlich, Fellow of this Society since 1941, and Professor Emeritus of Astronomy in the University of St Andrews, died on July 24, 1964, at the age of seventy-nine at his home in Wiesbaden, Germany. Freundlich was born in Biebrich, Rheinland,

Germany, the son of a German father and an English mother, E. Elisabeth Finlayson, from Cheltenham. In 1910 he obtained his degree of Dr. Phil. for work carried out at Göttingen under the famous mathematician Felix Klein.

From the beginning of his career and throughout his life Freundlich was especially interested in Einstein's Theory of Relativity and in its astronomical applications, a subject on which he published several books and a number of papers (The Foundation of Einstein's Theory of Gravitation, Cambridge, 1920; The Theory of Relativity, London, 1924). In 1924 he created the Einstein Institute, with considerable financial support from German industrial and commercial circles, in the grounds of the Astrophysical Observatory, Potsdam, Germany. This first European solar tower telescope with its large spectrographs, in its whole scientific design and architectural style, was well ahead of its time (Das Turmteleskop der Einstein-Stiftung, Berlin, 1927). Freundlich's leadership of a lively and active team soon made the Einstein Tower a centre of modern astrophysics which attracted many visitors from abroad.

In 1926 and 1929 Freundlich organized two carefully planned and specially equipped solar eclipse expeditions, both to Sumatra. Their main purpose was to verify the gravitational light deflection predicted by Einstein's theory, at that time a task of fundamental importance. The expedition of 1929 was particularly successful: it gave for light deflection a result with one of the smallest mean errors ever obtained. (Abh. Preuss. Akad. Wiss., Nr. 1, 1931, Phys. Math. KI.). The observed deflection, however, exceeded the predicted one. This apparent tendency towards a slightly larger observed value was found also by other measurements of the light deflection and Freundlich carried out several special investigations in an attempt to clear up this discrepancy (Z. Astrophys., 6, 218, 1933).

In 1933, when the Nazis seized power, Freundlich, like many German scientists, left Germany for good, abandoning all he had so successfully created at Potsdam, and went to Istanbul. There he brought into being a new department of astronomy and wrote also the first textbook on astronomy to be published in Turkish. In 1936 he was appointed Professor in the University of Prague, building up there another astronomical department. Once again he had to leave when in 1939 the Nazis extended their power farther to the east. He was fortunate in obtaining an astronomical appointment in Scotland where he was to stay for the next twenty years.

Sir Peter Radford Scott Lang, for several decades Regius Professor of Mathematics in the University of St Andrews, had always hoped that one day a lectureship in astronomy would be founded at St Andrews. His daughter, Miss Edith Mary Valentine Scott Lang, made this possible by a bequest to the University and in 1939 Freundlich was appointed to the new lectureship. In 1951 a Chair of Astronomy was formally established, with which Sir Peter Scott Lang had expressed a wish that the name of Baron Napier of Merchiston should be associated. On January 1, 1951, Freundlich became the first Napier Professor of Astronomy in the University of St Andrews, a post which he held until his retirement in 1955.

When appointed to St Andrews he immediately began to build up a new department of astronomy; the initial observatory building had been completed as early as 1940. During the war the department was used mainly for lectures on navigation to personnel from neighbouring airfields and Freundlich published a booklet on air navigation (Air Navigation, Edinburgh, 1945). During his years in St Andrews, Freundlich was occupied chiefly with various problems in the field of stellar dynamics (Mon. Not. Roy. Astr. Soc., 107, 268, 1947), celestial mechanics (Celestial Mechanics, London, 1958; Cosmology, Chicago, 1951), and relativity (Mon. Not. Roy. Astr. Soc., 104, 40, 1944). In particular he published, with a number of collaborators, papers on the problem of the empirical confirmation of gravitational light deflection and of the relativistic red-shift of solar spectral lines which fascinated him all his days (Phil. Mag., 45, 303, 1954; Proc. Phys. Soc. Lond., 67A, 192, 1954; Ann. Astrophys., 19, 183, 1956; ibid., 19, 21S, 1956; ibid., 22, 727, 1959).

In addition to his lectures one of his main tasks was the setting up of a refracting telescope for St Andrews University. The year 1949 saw the completion of the 17-inch pilot model of a special Schmidt-Cassegrain telescope, the optical design of which was due to Dr E H Linfoot of Cambridge (Schmidt-Cassegrain Telescope of Dundee, Nature, Lond., 165, 703, 1950). The pilot instrument was given practical tests at the Mills Observatory, Dundee, and it was so successful that it was decided to build, partly in the Observatory's own workshop at St Andrews, a larger model of 37 inches (A New Telescope in Scotland, Sky & Telese., 12, 176, 1953). This was a major undertaking, but in Mr R L Waland, the chief mechanic of the Observatory's workshop, Freundlich found a very skilful optician and collaborator. Following his retirement in 1955, Freundlich held a temporary appointment in the University of St Andrews to enable him to continue with the telescope project. In 1957 he went to live in Wiesbaden, where he had had a new house built, but he continued to make frequent visits to St Andrews in his capacity of Director of the Observatory until his successor was appointed in 1959 (Nature, Lond., 184, 768, 1959). However, the telescope was far from complete by that time.

The laboratory of the Observatory was used at that time for an investigation into the technique of producing multicoated interferometer plates (Dr A H Jarrett) (Z. Astrophys., 34, 91, 1954). Such plates were used subsequently with very good results on several solar eclipse expeditions (1954, 1955, 1958), undertaken in collaboration with the Cambridge University Observatories, for observations of the emission lines of the solar corona. At the same time the successful nucleus of a geophysical group for observing night glow and for auroral studies came into being at the Observatory in St Andrews. Freundlich himself retained a keen interest in the measurement of relativistic light deflection. Through the kindness of the Astrophysical Observatory in Potsdam he arranged that the specially large Potsdam equipment, which he had used so successfully at the 1929 eclipse for the same purpose, should be used once more for an eclipse expedition in 1954 in which he himself took part. The arrangement was repeated in 1955. Unfortunately, bad weather prevented success on both occasions. In his later years Freundlich was intensely interested also in the question of whether there might exist an as yet unknown photon-photon reaction in radiation fields which, if existing, might influence the measurement of light deflection as well as that of the relativistic red shift of spectral lines (Nachr. Ges. Wiss. Göttingen, 1953, 95: Z. Astrophys., 58, 283, 1964).

In 1955 Freundlich had been appointed Professor Emeritus at St Andrews University at the age of seventy. At the age of seventy-four he made his last official visit to that University and finally settled in his home in Wiesbaden, but not in retirement: even there he remained active, lecturing as an Honorar-professor at the nearby University of Mainz.

Freundlich was unfailing in his kindness and helpfulness towards colleagues and friends, both in scientific and in personal matters. He was always prepared to organize new research facilities for his staff and to obtain all possible support for his collaborators even under difficult conditions. As one of his collaborators at St Andrews expressed it: 'problems, either academic or personal, were always of interest to him and I have never known him not to make time for a talk on almost any subject'. By nature he was of a kind and generous disposition and on several occasions he came to the assistance of genuinely impoverished students. This tall, distinguished man will long be remembered with affection by his staff and by the students of his era at St Andrews.

Erwin Finlay-Freundlich's RSE obituary by H von Klüjber appeared in Royal Society of Edinburgh Year Book 1965, 13.

(See also complete Bibliography in Astronomische Nachrichten, 288, No. 5/6, 1965.).