Telegraphy the sense of a system that can transmit arbitrary messages over arbitrary distances. Lines of signalling relay stations can send messages to any required distance, but all these systems are limited to one extent or another in the range of messages that they can send. A system like flag semaphore, with an alphabetic code, can certainly send any given message, but the system is designed for short-range communication between two persons. An engine order telegraph, used to send instructions from the bridge of a ship to the engine room, fails to meet both criteria; it has a limited distance and
International Code of Signals the Commercial Code. It came in two parts: the first containing universal and international signals, and the second British signals only. Eighteen separate signal flags (see chart) were used to make over 70,000 possible messages. Vowels were omitted from the set to avoid spelling out any word that might be objectionable in any language, and some little-used letters were also omitted. It was revised by the Board of Trade in 1887, and was modified at the International Conference of 1889 in Washington, D.C. The new international code of signals officially came into worldwide operation on 1 January 1901. At first