‎"BOHR, NIELS.‎
‎Determination of the Surface-Tension of Water by the Method of Jet Vibration. Offprint from: Philosophical Transactions of the Royal Society of London, Series A, Vol. 209. pp. 281-317. - [BOHR'S FIRST PUBLISHED PAPER - PRESENTATION COPY]‎

‎Determination of the Surface-Tension of Water by the Method of Jet Vibration. [Offprint from: Philosophical Transactions of the Royal Society of London, Series A, Vol. 209. pp. 281-317.] - [BOHR'S FIRST PUBLISHED PAPER - PRESENTATION COPY]‎

‎(London, Harrison & Sons, 1909). Large 4to. Original printed wrappers" wrappers loose and with lack of paper, mostly to back wrapper, which is quite chipped and nicked, with tears, and lacking a bigger part of the upper right corner. Front wrapper merely lacking a few smaller pieces at the top, not affecting the presentation inscription. Pp. 281-317.‎

‎Extremely scarce first edition, off-print issue with presentation-inscription, of Bohr's first published paper, constituting his only ever work in experimental physics. ""His first research project, a precision measurement of the surface tension of water by the observation of a regularly vibrating jet, was completed in 1906, when he was still a student, and it won him the gold medal from the Academy of Sciences. It is a mature piece of work, remarkable for the care and thoroughness with which both the experimental and theoretical parts of the problem were handled."" (DSB).The work is inscribed to renowned Danish physicist and meteorologist Dan la Cour (1876-1942), son of the great Poul la Cour (1846-1908), who is considered the ""Danish Edison"". The inscription reads as thus: ""Hr. Docent D. la Cour/ ærbødigst/ fra/ Forfatteren."" [In Danish, i.e.: ""Mr. Assistant Professor D. la Cour/ with great respect / from/ the author.""].Dan la Cour was the assistant of Niels Bohr's father, Christian Bohr, and a well known scientist. From 1903, he was head of the department of the Meteorological Institute, and from 1923 leader thereof. From 1908 he was Associate Professor at the Polytechnic College. His original scientific works are highly respected, as are his original apparati for measuring earth magnetism which are considered highly valuable. ""His original intelligence, which in many ways resemble that of his father, also bore fruit in his patenting of various inventions: the ""Pyknoprobe"", developed to quickly determine the different layers of the sea"" a use of termite in quickly heating food and drinks out in the open under unfavourable weather conditions."" (From the Danish Encyclopaedia - own translation). He wrote a number of important and esteemed works and was member of the Danish Scientific Academy as well as many prominent international scientific commissions of meteorology and geophysics (i.e. president of the International Geodetical and Geophysical Union). He was also honorary Doctor at the George Washington University. This Bohr's fist paper grew out of a work which Bohr did in 1906, and for which he won a gold medal from the Academy of Sciences. The subject was to experimentally investigate a method, proposed by Lord Rayleigh, for measuring the surface tension of water by the observation of a regularly vibrating jet. ""Bohr [...] included in his work essential improvements on Rayleigh's theory by taking into account the influence of the liquid's viscosity and of the ambient air, and by extending the earlier theory from infinitesimal to arbitrary large vibration amplitudes. In order to execute his experiments he had first of all to cope with one complication. The university had no physics laboratory."" (Pais, p. 101). Bohr thus constructed many of the instruments himself using his father's laboratory. """"I did the experiments completely alone alone in the physiological laboratory... it was a great amount of work"", which was technically demanding."" (Pais, p. 102). In spite of being Bohr's only ever work in experimental physics, it documents his deep understanding of the methods of experimentalists.""On 23 February 1907 the Academy notified him that he had won its gold medal. In 1908 he submitted a modified version to the Royal Society in London. It was his first and last paper on experiments he himself performed. His second publication was his last to deal with surface tension of liquids"" it was purely theoretical. Both papers were favorably referred to in later literature.The manuscript of the prize essay, never published in its original form, is preserved in the Bohr Archives. It is handwritten, by Harald Bohr [i.e. his brother]."" (Pais, p. 102), Rosenfeld, Bohr Bibliography No. 1. Rosenfeld, Dictionary of Scientific Biography II, pp. 239. Pais, Niels Bohr's Times, pp. 101-02.‎