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Telegraphy, Equipment Heurtley magnifier, 1919

Telegraphy, Equipment Heurtley magnifier, 1919
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Not available to clients invoiced in the UK
Largest available format 3278 × 3504 px 1 MB
Dimension [pixels] Dimension in 300dpi [mm] File size [MB] Online Purchase
Large 3278 × 3504 px 278 × 297 mm 1.3 MB
Medium 958 × 1024 px 81 × 87 mm 995 KB

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IMAGE number
UIS5060773
Image title
Telegraphy, Equipment Heurtley magnifier, 1919
Auto-translated text View Original Source
Artist
Unknown
Location
Science Museum, London, UK
Medium
object
Image description

Telegraphy, Equipment Heurtley magnifier, 1919. The Heurtley magnifier was a way of detecting weak telegraph signals in the pre-electronic era, and is based on the Wheatstone bridge developed by Charles Wheatstone (1802-1875) in 1843. When the bridge is balanced, a detector connected to it shows no response, but small changes in balance have a great effect. It used incoming telegraph signals passing through an electromagnet to move hot wires in and out of a cooling air blast. The resulting changes in balance operated a relay, which switched the larger currents needed to drive the recording equipment. Shown out of its case. ©SSPL/Science Museum

Photo credit
SSPL/UIG / Bridgeman Images
Image keywords
20th century / thing / 1910's / communication / Telegraph - Telegraphy / tool / progress / message / Science / photography

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