Portrait of Henry Moseley (1887-1915), English physicist and developer of X-ray analysis. Moseley was a gifted student, winning scholarships to Eton and Oxford. Moseley developed the ideas of Laue and the Braggs on X-ray refraction, showing that the characteristic wavelength of each element was in direct relationship to the number of protons in the nucleus. This allowed a fine-tuning of Mendeleev's periodic table of elements which was ordered by atomic weight, and showed that only 92 elements could exist from hydrogen to uranium. This X-ray analysis was used to confirm new discoveries. Moseley was killed at Gallipoli in 1915 whilst serving in the Royal Engineers.