History of the Arabic alphabet the same. After all this, there were only 17 letters that were different in shape. One letter-shape represented 5 phonemes ("b t th n" and sometimes "y"), one represented 3 phonemes ("j ħ kh"), and 5 each represented 2 phonemes. Compare the Hebrew alphabet, as in the table at . A similar ambiguity occurs in the German Fraktur font, in which the Roman alphabet uppercase letters I and J look the same but are officially different letters. The Arabic alphabet is first attested in its classical form in the 7th century. See PERF 558 for the first surviving Islamic Arabic
American Morse code a type of distortion called dispersion that gets progressively worse with the length of the cable. Dispersion severely limits the rate that Morse can be sent because of intersymbol interference. For instance, the first transatlantic telegraph cable of 1858 could only sustain a transmission rate of less than 1 word per minute. This interference is worse with American Morse because it has a greater proportion of closely spaced dots than the Gerke code. The Gerke code was adopted as a standard for transmission over cables by the Austro-German Telegraph Union (which included many central European states) at a conference in