Letter: Letters: First fax

From RICHARD GREGORY

Your interesting account of ‘The world’s first fax machine’ (In Brief,
13 June) did not take note of the earlier and conceptually much more sophisticated
fax invented by F. C. Bakewell, who lived in Haverstock Terrace in Hampstead.
Bakewell described his ‘copying telegraph’ very clearly in his book, Electric
Science: Its History, Phenomena, and Applications, published in 1853. Not
only was this 13 years earlier than Caselli’s pantelegraph, but it solved
the synchronising problem without the need of independent accurate clocks.

Using tin foil and non-conducting ink for transmission, with Davy’s
electrochemical method of marking the paper, the six-inch -diameter transmitting
and receiving drums were rotated with falling weights and air fans, adjusted
so that, left to themselves, the receiving drum rotated slightly faster
– but they were not left to themselves. Synchronising pulses were transmitted
(12 per drum rotation) which actuated a solenoid for an intermittent brake
on the receiving drum. So this was an early feedback device. Bakewell also
describes the use of pendulums, which he preferred for single wire operation;
these also were synchronised with pulses, to a regulating magnet, and so
did not need to be extremely accurate clocks. Any error (especially when
setting the system up) was made visible by drawing automatically a vertical
reference strip which tilted if the drums rotated at different speeds.

The line scanning was done with a single fine screw thread, as in an
Edison cylinder phonograph (invented in 1877). So printing was by a continuous
line, about 10 rotations being needed to form a row of letters. Bakewell
claimed a normal writing speed of 300 words a minute. He could send confidential
handwritten messages using a chemical ‘invisible ink’.

Bakewell concludes that he had ‘received the assurance of some scientific
gentlemen who have been longest and the most successfully engaged in such
undertakings, that the copying of writing is the beau-ideal of telegraphic
communication, and that sooner or later it must supersede all other means
of corresponding by electric telegraph’. Not bad for 139 years ago.

Richard Gregory University of Bristol