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Characters in Rutherford's life

Harry Moseley (1887-1915)

“Henry Gwyn Jeffreys Moseley. Born Nov. 1887. Killed in the Great War at Gallipoli. August 10, 1915. ”

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Words appearing on the back of the photo below, handwritten by Amabel Moseley, mother of HGJ (aka Harry) Moseley.

Harry Moseley 1910.jpg

Pictures:

   By the time he entered the First World War in 1914, Harry had been working for a year in Oxford, where he had graduated last. Before that, he had been part of Ernest Rutherford's research team in Manchester from 1910 to 1913.
   It was there that he had started experiments on X-rays, providing evidence for Rutherford and then Bohr atomic models and establishing "Moseley's law" which explains the order of atoms in the periodic table, by linking by a mathematical formula their "atomic number" at the frequency of the X-rays emitted by each element.
  Manchester's specialty was Rutherford's, namely radioactivity. He was therefore reluctant to see Moseley take an interest in any other subject. But he allowed him to invest himself in X-rays, because he knew that a passionate researcher is more efficient than a forced researcher; and he considered Moseley to be an exceptional experimenter; and he knew the sharpness of his mind.

Henry%20G.J_edited.jpg
Correction paper dec 1912 Phil mag by Er

   He had paid the price himself when, in mid-October, Harry had pointed out an error to him in his last article published that same month in the Phil Mag.

  Rutherford had forgotten to integrate relativity (a theory he did not master, unlike Moseley) in his calculations. The boss had grumbled in front of his assistant that it did not change the conclusions of the article, but had recognized the interest of the remark and drafted on November 4, a letter of correction which he sent for publication in the December issue of the Phil Mag.

" Mr. Moseley drew my attention to the fact, which I had overlooked, that according to the Lorentz-Einstein theory, the total energy E of the electron is not given by the above formula, but by E = (followed the corrected formula) ".

  At 25, getting a retraction from one of the greatest physicists of the time, Nobel Prize winner and director of the world's most successful research laboratory, was a great achievement for Harry Moseley. But it was no wonder that this was possible, knowing Rutherford's personality.

  He was known to never or almost never make a mistake (while being a bit cavalier at times with handling mathematical tools).  Actually, he usually published an article only when he was certain of his conclusions, proven by rigorous experiments and possibly based on the opinions of his assistants or students.

  However, on the first occasion that he published an erroneous article, it seemed obvious to him that he had to recognize it and above all put forward the name of the person who had corrected it. Despite his reputation, his prizes and his medals, Professor Rutherford put science and its progress well before his self-esteem. A principle that not all scientists complied with.

  What followed showed him that he had been right to let Moseley decide on his research path, given the results mentioned above. In addition, this study of X-rays earned other researchers in the field the attribution of the Nobel Prizes in physics 1914 (Max von Laue) and 1915 ( William Henry Bragg and William Lawrence Bragg ). The 1916 one would have had a good chance of going to Harry Moseley (who had already been nominated in 1915, for both the physics and chemistry prizes, by Svante Arrhenius, as indicated on the Nobel website).

  On August 10, 1915, in Gallipoli, the 27-year-old physicist was shot in the head. That was the end of one of the most promising careers in science at the beginning of the 20th century.

Bataille des Dardanelles.png
Moseley death announcement.jpeg
Greece and Turkey showing Gallipoli.gif

Situation of the Dardanelles strait

& map of the Gallipoli peninsula.

Sources: National Archives UK & Wikipedia

Source : Find a Grave

Moseley obituary by Rutherford - Nature

First lines of the obituary written by Ernest Rutherford for the journal Nature, September 9, 1915 issue

SCIENTIFIC men of this country have viewed with mingled feelings of pride and apprehension the enlistment in the new armies of so many of our most promising young men of science - with pride for their ready and ungrudging response to their country's call, and with apprehension of irreparable losses to science. These forebodings have been only too promptly realised by the death in action at the Dardanelles, on August 10, of Henry Gwyn Jeffreys Moseley, 2nd Lieut. in the Royal Engineers, at the age of twenty-seven.

Raies d'émission du calcium au zinc - Z

The image opposite shows the photographic plates used by Harry Moseley in 1914 (he was then stationed in Oxford).

We see lines corresponding to the frequencies of X-rays emitted by various chemical elements (examples: Cu, Ni, CO, Fe are respectively copper, nickel, cobalt, iron).

Moseley demonstrated that these frequencies increase as the atomic number of the elements increases. He thus demonstrated that the elements could be classified according to this atomic number and not according to the "atomic weight" (one says today "atomic mass"), as Mendeleev had done in 1869 in his famous table. This explained why Mendeleev's classification had to undergo some adjustments.

Moseley also established that this atomic number was not only an arbitrary order number, but that it corresponded to the number of positive charge contained in the nucleus of different atoms, thus supporting Rutherford's atomic theory.

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The video below shows the progress of his experiments.

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