Their system was soon being used for railroad signaling in Britain.
All the system needed was a key, a battery, wire and a line of poles between stations for the wire and a receiver.
These limitations also lessened the effectiveness of the semaphore, a modern precursor to the electric telegraph.
Developed in the early 1790s, the semaphore consisted of a series of hilltop stations that each had large movable arms to signal letters and numbers and two telescopes with which to see the other stations.
Like ancient smoke signals, the semaphore was susceptible to weather and other factors that hindered visibility.
A different method of transmitting information was needed to make regular and reliable long-distance communication workable.