50 Years Ago

'The Delhi Pillar' — The mystery which has enveloped this quite remarkable piece of metal should be once and for all removed as a result of three papers published in the ... Journal of the National Metallurgical Laboratory of India ... All that has been previously written is summarized and the theories propounded to explain its resistance to corrosion are collected ... Made by hammer-welding small balls of native iron ... its resistance to corrosion during the 1,600 years or so of its existence is ascribed to the combined influence of a number of normal, favourable factors. Among these are included the climate and freedom from pollution of the atmosphere. Secondly, to a progressively decreasing rate of attack due to the building up of a protective layer of oxide and scale during the early years of exposure. That in the past on ceremonial occasions the pillar was anointed appears to be probable ... This is supported by the X-ray analysis of a minute sample of the surface coating ... which contained no iron and only quartz and chalk providing another source of protection.

From Nature 3 August 1963

100 Years Ago

We have applied the new methods of investigation involving the use of X-rays to the case of the diamond, and have arrived at a result which seems of considerable interest. The structure is extremely simple. Every carbon atom has four neighbours at equal distances from it, and in directions symmetrically related to each other. The directions are perpendicular to the four cleavage or (III) planes of the diamond; parallel, therefore, to the four lines which join the centre of a given regular tetrahedron to the four corners. W. H. Bragg & W. L. Bragg

From Nature 31 July 1913