Lynn Korwatch located on top of Telegraph Hill. George F. Sweeney and Theodore F. Baugh were the two individuals to present the idea of a wooden semaphore on top of Telegraph Hill. A semaphore is a system in which one uses two flags or poles and sends signals in an alphabetic code. Sweeney and Baugh expanded their system by placing a signal station on Point Lobos, which is located 20–30 miles from port in San Francisco. The reasoning behind this was that there was high demand from people wanting to know when the ships were arriving at an earlier time so that
International maritime signal flags with duplicate characters to be signaled without the need for multiple sets of flags. The four NATO substitute flags are as follows: The International Code of Signals includes only the first three of these substitute flags. To illustrate their use, here are some messages and the way they would be encoded: International maritime signal flags International maritime signal flags refers to various flags used to communicate with ships. The principal system of flags and associated codes is the International Code of Signals. Various navies have flag systems with additional flags and codes, and other flags are used in special uses,