Popham Telegraph Code
The calculator can convert English phrase to sequence of Popham Telegraph codes. It also can be use to decode a message encoded in Popham code.
The calculator below generates Captain Home Popham's telegraph code flags for any sentence in English. The code was used by the English navy during the Napoleonic Wars in the early 19th century.
Popham Telegraph Code
Popham signaling rules
The Popham signalling system uses 10 flags for the numbers 0 to 9 respectively :
.
Each hoist consists of one to four flags hoisted one below another. A message consists of words or sentences, each of which is encoded by an unique number 26-2998 in the dictionary . If a word is not in the dictionary, nearest synonym must be used. In worst case, a word can be spelled letter by letter. For this case numbers 1-25 are reserved for English letters (letter I and letter J has the same code - 9 ).
A flag hoisted alone, or under another flag, is to represent units. When two flags are hoisted, the upper flag is to represent tens. When three arc hoisted, the uppermost is to represent hundreds, the next tens, and the lowest units. The thousands are denoted by pendants or balls, as may appear most likely to be seen, inferior and superior: superior, 1000; inferior, 2000. When the substitute flag 
is hoisted under other flags, it is to represent the same figure as the flag immediately above it.1
E.g.
 |
1122 - Bottom | |
2122 - I have lost a cable |
A message starts with diagonal red and whie flag : 
, it finishes with a diagonal blue and yellow flag: 
.
The receiving party must repeat the received signal or display an affirmative flag 
. If the message was not understood, affirmative flag with white pedant under it must be hoisted. When any particular number in a message is not understood, it is to be expressed by hoisting the numerical pendant 
, with the number of the word or sentence beginning from the first word.
|
Message understood |  |
Message not understood | |
4th word not understood |
Popham code application
The first edition of the Telegraphic signals or Marine Vocabulary was issued in 1800th. It contained about 1000 words with codes 26-996. Three years later, seeing the many advantages of using telegraph signals, Sir Home Popham decided to expand it by adding two more parts. The second parts contains another portion of words (1026-1996) alphabetically sorted opposite to the first part words. The third part consists of sentences most applicable to military or general conversation (codes 2026-2994).
In the 1803th the Marine Vocabulary was adopted by the admiralty. The Popham Telegraphic code become widely known after the battle of Trafalgar that took place on 21th October 1805 between Royal Navy and joint Franco-Spanish fleet.
Before the battle, admiral Horatio Nelson hoisted the famous signal England expects that every man will do his duty on his flagship HMS Victory. Original phrase, requested by Nelson was England confides that every man will do his duty. But since the word "confides" is not int the Marine Vocabulary, John Pasco, Nelson's flag officer suggested to replace it with "expects", that allowed to shorten whole message by 7 flag hoists.
Who knows what would have happened if John Pasco had had access to our calculator? If he had turned on the "Find synonyms" option, the phrase could have been shortened by another 3 flag lifts.: England expects that every man will do his obligation
Decoding tool
To browse the Popham's Marine Vocabulary, or lookup a word or a sentence by the code use the following tool:
Popham Marine Vocabulary
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Telegraphic signals or Marine Vocabulary by Sir Home Popham, 2nd Edition, 1803, Printed for T. Egerton, Military Library, Near Whitehall. ↩
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