370 BELL SYSTEM TECHNICAL JOURNAL 



This was provided for by a system of selectors (of types used in dial 

 telephone apparatus) and relays. Sets of contacts corresponding to 

 the appropriate lamps on the translucent screen in front of the caller, 

 that is, to the 22 initial consonants, 22 final consonants, and the 11 

 vowels (in duplicate), were arranged so that the order in which they 

 were swept over was varied mechanically in a random way. The 

 mechanical rearrangement of the contacts, which prepared a group of 

 22 syllables, required about two seconds. Of this time, only 0.3 

 second was needed to set up a new group. The remaining 1.7 seconds 

 were used by the machine in checking over the group to see that the 

 syllables were satisfactory. The need for this is plain. Certain com- 

 binations of sounds, being impossible to pronounce, must be rejected, 

 and certain others must be eliminated, as having undesirable meanings 

 in English. Additional relay systems were provided so that during 

 a rapid preliminary run the presence of such undeired combinations 

 or syllables would cause the group to be rejected automatically, that 

 is, the machine would be returned to its normal position and a new 

 group would be set up. The checking process was repeated until a 

 suitable list was obtained. 



The apparatus used by the callers and observers with the first 

 machine is the same as that used with the present equipment. The 

 final record differed in being a photograph of a bank of 60 message 

 registers (electromechanical counters), which classified the errors by 

 individual sounds in addition to showing the total number of sound 

 errors made by each observer. This bank of message registers was 

 photographed automatically at the beginning and at the end of the 

 calling of a list of 66 syllables. At the end of a test the photographs 

 were developed, washed and dried by other mechanical apparatus, the 

 final record appearing in about two minutes. 



While this equipment demonstrated effectively the value of rapid 

 mechanical analysis of the data, it was felt desirable to simplify it and 

 extend its usefulness by adding certain other features. This seems to 

 be satisfactorily attained by the present machine, which not only is 

 simpler to operate and maintain, but offers as well greater flexibility 

 in the lists which may be used and in its adaptability to phonographic 

 calling. 



