Die Grundlagen der Einsteinschen Gravitationstheorie. Mit einem Vorwort von Albert Einstein.

Berlin: Julius Springer, 1917. Duodecimo. Original cream wrappers printed in black. 1 leaf of publisher's ads at rear. Short pencil note to upper wrapper. Wrappers toned and rubbed with a few small marks, creases and nicks. Contents fresh. A very good copy. Second impression (originally published the previous year) of this proposal for testing Einstein's theory of relativity by the astronomer Erwin Finlay-Freundlich (1885-1964). Freundlich knew Einstein well during the period when they both lived in Berlin, and astronomical proofs of Einstein's theories were among his major research interests. "The quest for high accuracy in the measurement of the redshift in the solar spectrum led him to plan the building of the famous Einstein tower in Potsdam. he was also involved in some of the earliest attempts to measure the deflection of starlight during eclipses. In the summer of 1914 he led an expedition to the Crimea to observe a total solar eclipse. Caught by the outbreak of the First World War, he and some of his party were interned by the Russians as enemy aliens. Fortunately, the group was soon exchanged for some Russian officers who had been early taken as prisoners of war" (Batten "Obituary: Erwin Finlay-Freundlich", Journal of the British Astronomical Association, issue 1, vol. 96, p. 33, 1985). It is possible that this failure led to the rapid acceptance of general relativity several years later. "Einstein had not completed his work on that theory in 1914, and was predicting a deflection of starlight... only half the value that he gave in the definitive paper of 1915. Had Freundlich been successful in 1914, he would thus have found twice the expected value, and Einstein's later paper, instead of appearing as a brilliant predication, might have seemed an ad hoc adjustment of the theory to fit the observations" (Batten, p. 33).