cr.RT.iix i:iCTORs .trrncTiXi, i i.i.i ui^.iin .■sri.i-.i) .w 



elements, may be clelermined approximately hy the follnwiny; formula, 

 the derivation of which is given in Appendix M. 



Where \V is the spx-etl of transmission of intelligence, 



m is the number of current values, 

 and. K is a constant. 



By the si>eed of transmission of intelligence is meant the number of 

 characters, representing ditTerent letters, figures, etc., which can be 

 transmitted in a given length of time assuming that the circuit trans- 

 mits a given number of signal elements per unit time. 



Substituting numerical values in this formula gives the following 

 table which indicates the possibilities of speeding up the transmission 

 of intelligence by increasing the number of current \alues. 



Relative .Amount of 

 Intelligence which can 

 be Transmitted with a 

 Nllmlx^r of Current Given Number of 



\'alues Employed Signal Klcments 



2 100 



3 158 



4 200 



5 230 

 8 300 



16 400 



This table indicates that there is considerable advantage to be 

 secured in going to more than two current values where the circuits 

 are such as to permit it and where the line speed is not lowered as a 

 result. The limitations will be outlined below. It should also be 

 noted that whereas there is considerable advantage in a moderate 

 increase in the number of current values, there is little advantage in 

 going to a large number. 



Codes Now in Common Use — Co.mp.vrison with Iue.vl 



In the case of printer codes, the theoretical results derived corre- 

 spond closely to practise, as will be obvious from the method of 

 deriving the formula. 



In order to compare the theoretical possibilities indicated by the 

 formula with the results which are obtained when non-printer codes 

 are constructed, several codes were assumed, and for each one the 

 number of signal elements required to produce an average letter 



