Manual telegraph

'The military anthropo-telegraph for field-service. Represented at work, in giving a phrase from the dictionary.'John MacDonald (1759-1831) was a civil and military engineer and cartographer with the East India Company, and served in India and Sumatra. His work on the magnetic needle was to earn him election as a fellow of the Royal Society in 1800. However, it was only through the work of Michael Faraday and Sir Charles Wheatstone on electromagnetism that the magnetic needle came into its own as an essential component of the telegraph.

The second part of this book comprises a telegraphic dictionary, in which numerical values are assigned to thousands of words and phrases for use in signalling. Such a system could be applied to a wide range of signalling methods, including semaphore towers or the ‘anthropo-telegraph’, a human signaller using flags, as shown here in the fold-out illustration.

When this book was published, Britain had just endured its most pressing challenge from a military opponent since the 1660s. It was with this danger in mind that MacDonald made his detailed proposal for a system of telegraphy which would use a cipher system to transmit numbers representing individual words. He also predicted its utility for commerce. The authorities refused to take his proposal seriously, because his system could lead to serious errors through the faulty transmission of only a single number.

The Admiralty had in fact built a telegraph for communications from London to Portsmouth in 1796. This was a variation on the inventor Robert Hooke’s scheme of 1684 in which large boards or shutters of various shapes could be hung in a wooden frame to convey, by their shape, different letters of the alphabet, and then viewed from a distance by using a telescope. After the Napoleonic Wars, the cumbersome shutter system was abandoned in favour of French semaphore telegraphy.

This copy is inscribed by the author.

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