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Joined 2026-09-21 Message
Incoming links: William Henry Bragg
By William Henry Bragg. Philosophical Transactions A 215, 253–274 (1915). Lecture delivered 18 March; manuscript received 7 April 1915.
Bragg crystal reflection experiment of 1913 2026-10-18
William Lawrence Bragg introduced the plane interpretation; his father William Henry Bragg built the X-ray spectrometer. Their joint 1913 paper, The Reflection of X-rays by Crystals, reports the experiment. [ref]
The Bragg law (University of Leeds Library Special Collections). The Bragg law: Lawrence's 1912 interpretation and the angle convention
[ref]William Bragg's spectrometer (Royal Institution collection). Description: William Henry Bragg designed and made the spectrometer
An X-ray tube supplied radiation through lead slits to a crystal mounted with its cleavage face through the rotation axis. A rotating ionization chamber replaced a spectrometer telescope; electric current measured the scattered signal, and a circular scale supplied angular readings. They first scanned the chamber at fixed crystal orientation, then swept crystal and chamber together to follow the reflection. [ref]
The Reflection of X-rays by Crystals by William Henry Bragg and William Lawrence Bragg. Bragg and Bragg (1913), pp. 428–430: preparation, source, slits, chamber, angular scale and scanning
Changing chamber gas checked detector dependence; readings on opposite sides checked face-setting errors. Repeated peaks with sines of half-deflections in integer ratios, together with matching absorption coefficients, distinguished repeated diffraction orders of the same wavelength from different radiation components. Comparing crystal faces constrained interplanar spacings. Their limits included slit broadening, face alignment and incomplete interception at glancing incidence; assigning absolute wavelengths still required a structural choice for . [ref]
The Reflection of X-rays by Crystals by William Henry Bragg and William Lawrence Bragg. pp. 428–430: gas and alignment controls; pp. 435–437 and Fig. 3: order comparison, absorption test, finite-face limitation and spacing ambiguity
William Lawrence Bragg's 1913 structure paper connects a slit-selected beam, an oriented crystal and an ionization chamber to strength-versus-angle curves. Repeated sine ratios and matching absorption coefficients identify common radiation. Narrower slits resolve blended lines. Absolute wavelengths remain undetermined there; intercrystal comparisons first give relative scales. The Bragg crystal reflection experiment of 1913 covers the alignment controls.[ref]
The Structure of Some Crystals as Indicated by their Diffraction of X-rays by William Lawrence Bragg. pp. 268–272, especially Fig. 16: angular ionization scans, order/absorption comparison, slit resolution and wavelength-scale limitation
William Henry Bragg's 1915 Bakerian lecture, X-rays and Crystal Structure, separates the geometric and intensity arguments. Its Figure 9 compares reflection positions and strengths from three sodium chloride orientations; odd and even diffraction orders differ in strength along one orientation. The interpretation uses alternating scattering layers. Later, the calcite example identifies an internal oxygen coordinate that symmetry alone cannot fix. Improved wave intensity measurements revise a previously rough estimate. Thus a lattice assignment can precede determination of positions inside the unit cell; intensity interpretation also has experimental and theoretical limits. This is the father's 1915 lecture, distinct from the joint 1913 reflection paper.[ref]
Nobel Prize in Physics in 1915 2026-10-18
Awarded jointly to William Henry Bragg and William Lawrence Bragg for methods of determining crystal structures using X-rays. Bragg's law connects measured angles to lattice-plane spacings.[ref]
The Nobel Prize in Physics 1915 by Nobel Prize Outreach. Official award record: laureates and crystal-structure subject
By William Henry Bragg and William Lawrence Bragg. Published in Proceedings of the Royal Society of London, Series A 88(605), 428–438, 1 July 1913. Received 7 April and read 17 April 1913.
Institutional scan: chair.itp.ac.ru/biblio/papers/ClassicPapersSeminar/Bragg1913a.pdf
Cited passages: pp. 428–430, apparatus and alignment check; pp. 435–438, repeated orders, absorption comparison and structural inference.
The Structure of Some Crystals as Indicated by their Diffraction of X-rays by William Lawrence Bragg 2026-10-18
By William Lawrence Bragg, credited as W. L. Bragg. Published in Proceedings of the Royal Society of London, Series A 89, 248–277 (1913). The first page records receipt on 21 June and reading on 26 June 1913. The communication credit to William Henry Bragg is distinct from authorship.
Inspected scan: scispace.com/pdf/the-structure-of-some-crystals-as-indicated-by-their-1ugl7pojiz.pdf
Cited passages: p. 248, authorship and communication credits; pp. 262–263, Figures 8–9 and Tables VII–IX, sodium chloride sections, orientations, thickness comparison and spot intensities; pp. 264–265, Figure 10, interpenetrating face-centered arrays and the remaining atomic-assignment uncertainty. The historical scattering-weight interpretation is not modern X-ray scattering theory.
Institutional museum record from the Royal Institution, crediting William Henry Bragg with designing and making the spectrometer. The object date, 1912, is distinct from the undated web record.
Collection record: www.rigb.org/explore-science/explore/collection/william-braggs-spectrometer