In the course of Peter Galison’s book-length study of the technological contexts of Einstein’s theory of relativity, he explains the role of attempts to synchronize clocks in large part as a means of creating accurate maps. Before the invention of wireless telegraphy undersea telegraph cables provided the only means of instantly communicating between great distances, and Great Britain both created and laid more such cables than all other nations together. First, one had to manufacture the cables. —
In Britain, especially, factories churned out prodigious quantities of cable. First, a thick copper conductor was insulated by commercial “gutta” —a newly developed mixture of gum, guttapercha, resin, and water. Then the manufacturers wound jute yarn to provide a cushion between the gutta-coated cable and a ring of thick iron wires to protect the copper core from breaking. More jute bound these iron wires together; then more wires with more yarn (at least near the dangerous rocky shore), and a final waterproof outer sheathing of the Malayan rubberlike gutta-percha. Steam-powered ships carried the mile-long sections out to sea, where onboard cable masters tied them together to span thousands of miles and sometimes hauled them out again when they (all too often) were split by sea life, icebergs, volcanoes, anchors, or sharp rocks. 
- The Laying of Submarine Cable — The Triumph of Brunel's Great Eastern on 27 July 1866
- Submarine Telegraphy Timeline
- Robert Dudley and The Atlantic Telegraph
Galison, Peter. Einstein’s Clocks, Poincaré’s Maps: Empires of Time. New York: W. W. Norton: 2003.
Last modified 3 December 2017