Abstract
Prof. Dame Kathleen Lonsdale was one of the two first female Fellows of the Royal Society, having originally been a student of that great British scientist and Nobel Laureate William Henry Bragg. She came to fame initially for her solution of the crystal structure of hexamethyl benzene, thus demonstrating that the benzene ring was flat, of considerable importance to organic chemistry, where it had been proposed before but without proof. This was at a time when the solution of crystal structures was in its infancy, and in its day this work was considered a triumph. As a rare example then of a female physicist, Lonsdale became interested in various aspects of the diffraction of X-rays, and in particular published an important paper on a form of diffraction in which a strongly divergent source was used rather than the usual highly collimated beam. The photographs thus obtained showed a series of arcs and circles, whose positions were so sensitive that they could be used to determine the quality of crystals such as diamond, and even to calculate their lattice dimensions, and hence carbon–carbon bond lengths, to hitherto extraordinary precision. Lonsdale also became known not just as a scientist but as a peace activist and an active member of the Society of Friends. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society.
Highlights
There ain’t nothing like a Dame: a commentary on Lonsdale (1947) ‘Divergent beam X-ray photography of crystals’
Dame Kathleen Lonsdale was one of the two first female Fellows of the Royal Society, having originally been a student of that great British scientist and Nobel Laureate William Henry Bragg. She came to fame initially for her solution of the crystal structure of hexamethyl benzene, demonstrating that the benzene ring was flat, of considerable importance to organic chemistry, where it had been proposed before but without proof
As a rare example of a female physicist, Lonsdale became interested in various aspects of the diffraction of X-rays, and in particular published an important paper on a form of diffraction in which a strongly divergent source was used rather than the usual highly collimated beam
Summary
Kathleen Lonsdale (née Yardley) (figure 1) was born in Newbridge, Ireland, on 28 January 1903 and died 1 April 1971 in London. These tables formed the basis for the International Tables for Crystallography which have become the standard reference on space group symmetry for all crystallographers today Following this she solved two very important crystal structures, those of hexamethyl benzene [6] and hexachlorobenzene [7]. In 1936, Kathleen [8] published a book, written entirely in her neat handwriting, entitled ‘Simplified structure factor and electron density formulae for the 230 space groups of mathematical crystallography’ on behalf of the Royal Institution This gave the mathematical relationships between possible X-ray diffraction amplitudes according to the space group symmetry of the crystal. Intensities of X-ray reflections were measured mainly on films by eye, by comparing spot intensities with a prepared scale, a most tedious process, and simple calculations when not using Pegasus were made with a FACIT mechanical calculator
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