image pp_52_16_17
Image number: RS.11608
Credit: ©The Royal Society

Spark discharge figure



Object type



height (drawing): 89mm
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.15 was produced in the same manner as the preceding, but on glass instead of card. As the dust is so very easily moved on glass, only one coil was used, and it is remarkable that the dispersive effect exhibited by the double positive wires is actually greater than that of the spark itself…’.

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 15 plate 10 in the published paper.

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