Telegraph Instrument - Henley, Double-Needle, circa 1855

Search the collections

Summary:: Double-needle magneto-electric telegraph instrument patented in 1848 and manufactured by Messrs Henley and Forster in England.

This instrument is an example of a double-needle telegraph system which did not require any source of electrical power such as a battery. The system was not widely used but was in operation on the Adelaide-Semaphore line in South Australia in the 1850s before being superseded by morse instruments.

The instrument had a large square dial on the sloping top of a wooden case, with two needles pivoted side by side on the dial. Pressing either of two levers, one on each side of the case, rotated a coil between the poles of a magnet and generated a pulse of electric current which was transmitted along the telegraph line to the receiving indstrument. There the pulse caused a deflection of one of the needles on the dial. The pattern of needle deflections indicated to the operator which letter of the alphabet was being received.
Description:: Wooden case with sloping top carrying a square dial. Two needles mounted side by side on dial. Dial marked with letters of the alphabet and corresponding needle deflection sequences. Two levers with paddle handles projecting from front of case, below front edge of sloping top. One lever on each side of instrument.
Acquisition Information:: Donation from Mr John Thompson, 1915

Discipline:	Technology
Dimensions:	350 mm (Height), 575 mm (Width), 660 mm (Length)

Tagged with:	telegraphy
Themes this item is part of:	J.J. Thompson - donor of telegraph objects to the Museum, Telegraphy Collection, Information & Communication Collection
Primary Classification:	COMMUNICATIONS
Secondary Classification:	Telegraphy
Tertiary Classification:	components
Inscriptions:	In centre of square dial: "Magnetic Telegraph Company HENLEY'S PATENT"
Manufacturer:	Henley & Forster, England, Great Britain, circa 1855
Patentee:	Mr William Henley, London, England, Great Britain, 1848 In 1848, W.T. Henley took out a patent for their double needle telegraph.
Collector:	Mr John Thompson, Armadale, Victoria, Australia, 27 Apr 1915
References:	http://books.google.com.au/books?id=6YwDAAAAQAAJ&;pg=PA107&lpg=PA107&dq=Henley+and+Forster+telegraph&source=bl&ots=9uPJFWceY8&sig=TvXar2W4xQurUHp3QEQ-ouy1ka4&hl=en&sa=X&oi=book_result&resnum=1&ct=result - accessed 3 December 2008