image pp_52_16_16
Image number: RS.11607
Credit: ©The Royal Society

Spark discharge figure



Object type



height (drawing): 66mm
width (drawing): 107mm



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.14. In this case the battery was discarded and sparks only from the combined coils were used, the same as in No.1. It shows the effect of splitting the positive current by the use of a double wire re-united at the sparking-point…the resting places of the dust ar every beautifully shown by the darkened spaces in this figure’.

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 14 plate 9 in the published paper.

The image is inscribed below in ink: ‘No.XIV’ and in pencil ‘1/2’. 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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