History of Science Museum: Collection Database Search


Henry 'Harry' Moseley and his experiments

Henry ‘Harry’ Moseley was an exceptionally promising young English physicist in the years immediately before World War I. His work on the X-ray spectra of the elements provided a scientific basis for the Periodic Table, contributed to the development of the nuclear model of the atom, and established X-ray spectroscopy as a means of scientific research which continues to the present day.


During his scientific research career spanning a mere 40 months, Harry worked under Ernest Rutherford at Manchester for three years before returning to his alma mater Oxford in 1913 for one year prior to enlisting in the Royal Engineers in October 1914 and going off to war.


Spanning his last year at Manchester in 1913 and his year at Oxford in 1914, Moseley developed an experimental setup using ingenious apparatus of his own design to significantly change the world of science. On 18 May 1913, Moseley wrote in private correspondence that X-ray spectroscopy "is sure to tell one much about the nature of the atom" but did not begin building the experimental apparatus until a few months later in early August 1913. [Heilbron, p83]

Moseley bombarded samples of chemical elements with electrons, a process which generates characteristic X-rays. He measured the X-ray wavelengths using a spectrometer. Moseley discovered that every chemical element’s identity is uniquely determined by its atomic number, this being the number of protons in its nucleus. With this experimental setup, Moseley provided a new order to and understanding of the periodic table of chemical elements - which was now sorted by atomic number rather than atomic mass – providing a new scientific framework to the table while also predicting four new chemical elements.


At Oxford, Moseley continued his experiments in the new Electrical Laboratory (now the Townsend Building of the Clarendon Laboratory) built in 1910.

Much of the Moseley apparatus held by the Museum of the History of Science was given to the museum by the Oxford University Physics Department in 1935 with the apparatus and some related graphs and documents having been gathered together and preserved by Professor John S. Townsend, an Irishman, mathematical physicist, and first Wykeham Professor of Physics at Oxford from 1900-1941.


Used by H.G.J. Moseley at the Electrical Laboratory, Oxford.


Donated by the Physics Department, University of Oxford, 1935.  See 'Accession Record: Extract from Annual Report for 1935' narrative.

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