image pp_52_16_24
Image number: RS.11615
Credit: ©The Royal Society

Spark discharge figure



Object type



height (drawing): 128mm
width (drawing): 120mm



Diagram created by sparking from Lord Armstrong’s machine for producing high tension electricity. These patterns were made in a powder of magnesium oxide (‘calcined magnesia’) and carbon black. The images were then photographed and drawings produced from them.

The author states in his paper that: ‘No.22 shows a circular barrier of six wooden hemispheres…formed round the centre of the dust plate, and the dust was swept off the inner space before making the experiment…the discharges were delivered from a Leyden battery…’.

Illustration from the manuscript version of the paper ‘On a multiple induction machine for producing high tension electricity, and on some remarkable results obtained with it’, by Lord Armstrong, Proceedings of the Royal Society, vol.52 (1892), pp.176-191. Printed as figure 22 plate 13 in the published paper.

The image is inscribed below in ink: ‘No.XXIII’ corrected in pencil to ‘XXII’ and ‘4/7’. Imprint details verso.

William George Armstrong, Baron Armstrong (1810-1900) armaments manufacturer and industrialist was elected a Fellow of the Royal Society in 1846.

Associated place

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