ALBERT EINSTEIN (1879-1955). "Hamilton'sches Prinzip und einheitliche Feld-Theorie". Autograph manuscript in German, unsigned, regarding the Hamilton's principle and Unified Field Theory. The manuscript contains a number of mathematical equations in his hand and original edits, cross-outs, and rewrites. First line reads: "Die in meiner früheren Arbeit über einheitliche Feldtheorie". Probably a draft of Einstein’s Session Reports of the Prussian Academy of Sciences, Physical-Mathematical Class of 21.3.1929.
7 pages, c. 275 x 220 mm. Written on thin paper, unsigned and undated (probably late 1920s or early 1930s). Page 1-3 written on three leaves, the rest on both sides, but numbered 4-5. Folded once, page 4 with another fold, minor spotting, minor tears to folds.

Probably originally from collections of Dr. Chaim Herman Müntz.
A copy of this manuscript is in the Albert Einstein Archives, Jerusalem, archival number 18-322.

Provenance: A Swedish private collection.

Chaim Herman Müntz (28 August 1884, in Łódź – 17 April 1956, in Sweden), Polish-German mathematician, now remembered for the Müntz approximation theorem. He was active in Berlin and Munich and worked closely with Einstein in 1927. In 1929 he was appointed professor at the University of Leningrad where he worked until he was expelled as a German citizen in 1937 when he moved to Sweden where he lived for the rest of his life. He collaborated closely with Einstein in the years following 1927, and his help is acknowledged in a number of papers. Müntz assisted Albert Einstein with complex mathemtical equations related to the physical theories he developed, including the unified field theory. In Einstein's published paper On Unified Field Theory (1929), the scientist expresses his appreciation of Muntz's 'laboriously precise calculation of the centrally symmetric problem on the basis of Hamilton's principle the results of his calculation suggested to me the method used here'.