
Jon Baddeley
Specialist Consultant Collectors, Science & Marine
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Sold for £637.50 inc. premium
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Specialist Consultant Collectors, Science & Marine

Head of Department
The striking egg-shaped form of the present example was replicated by numerous manufacturers throughout the 19th century, including William Ladd, Newton & Co, and Harvey & Peak. An electrical discharge is produced within the 'egg' once the air has been pumped out by a vacuum, and a high voltage connected to the terminal ring. The residual gas between the two rods is ignited under such conditions, and the distance between each rod can be adjusted manually.
Similar contemporary examples can be found in the Science Museum, London (Object No.1935-327), and the Royal Institution.