With these we have probably reached the final development of form so far as flag signals are concerned, for wireless has taken the place of visual signalling to such an extent that it is not likely that circumstances can now arise that will necessitate any radical recasting of the flag signal system. (v) COMMERCIAL CODES Some elementary flag signals, notably that for a pilot, were in use among merchantmen at least as early as the fifteenth century, but the first attempt to supply a code of signals suitable for merchant ships appears to have been that made by Sir Home Popham in 1804, when, at the request of the East India Company, he compiled a book of "Commercial and Military Signals" for the use of the ships in their service. In this book the "military" element preponderates, as might be expected from the circumstances of the time at which it was drawn up. The signals relate almost exclusively to the fighting and manoeuvring of ships sailing in convoy. After the peace, in 1817, Captain Frederick Marryat drew up what may be regarded as the precurser of modern commercial codes. It was in six parts, each in the simple numerary system, with a distinguishing flag to indicate the part to which the signal related. The parts were as follows: 1. Names of men-of-war. 2. Names of merchantmen. 3. Ports, headlands, etc. 4. Sentences on various subjects. 5 and 6. A vocabulary adapted from Popham. This signal book went through ten editions before the author's death in 1848. In 1855, owing to the enormous increase in communication by sea, and the adoption of an official number for every merchant ship imposed by the Merchant Shipping Act of 1854, the need for a much more ample code had become urgent, and the Board of Trade appointed a Committee to draw up a new one. This committee reported that an efficient code "ought to provide for not less than 20,000 distinct signals and should, besides, be capable of designating not less than 50,000 ships, with power of extension if required." They further stated that "a signal should not consist of more than four flags or symbols at one hoist," and pointed out that under this condition the ten numerals without repeaters would make only 5860 signals, or 9999 signals with three repeaters. They therefore abandoned the numeral system and chose 18 flags which, by using two, three, or four flags together, allowed of 78,642 permutations. These 18 flags, which embodied most of those already in use in Marryat's Code unchanged, or with slight alteration, were designated by the letters of the alphabet except a, e, i, o, u, x, y, z, the vowels being omitted because "by introducing them every objectionable word composed of four letters or less, not only in our own but in foreign languages, would appear in the code in the course of the permutation of the letters of the alphabet." The flags adopted were as follows: