image pp_52_16_20
Image number: RS.11611
Credit: ©The Royal Society

Spark discharge figure



Object type



height (drawing): 132mm
width (drawing): 127mm



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.18 shows another dust plate similarly treated [to no.17] but more lightly covered and without the glass tubes, instead of which two flat screens of cardboard…were fixed…’.

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 18 plate 11 in the published paper.

The image is inscribed below in ink: ‘No.XVIII’ 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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