Naval Journal from the shore Signal Station Caistor Norfolk, March 14 - September 8, 1807, wrapped in sail cloth and written by a half-pay Naval lieutenant and his assistant petty officer or midshipman
The primary purpose of the stations was to "interrogate passing ships and pass suspicions to the nearest naval base via the intermediate stations. A fast cutter or sloop would then investigate. To identify the location of the suspect ship, the message would include the number of the nearest 'principal station'... which also allowed the system to be used as a navigation aid..." in The Mariner's Mirror, 76: 4, 1990, p. 340












