88 



THE ELECTRIC TELEGRAPH. 



ing instrument according to the time which the key at the 

 transmitting station is held down. 



The general adoption of this system on the Continent some 

 years back occasioned the establishment of certain rules for 

 the settlement of the letters, numerals, &c., which have been 

 subsequently almost universally adopted. 



The formation of so many letters, &c., out of two 

 elementary signs required the greatest number of varia- 

 tions with the given number of elements. 



The number of variations, with repetitions of two elements, 

 are: 



With single signs 2 = 2 



With two signs 2 2 = 4 



With three signs 2 3 = 8 



With four signs 2 4 = 16 



Therefore, by using variations of from one to four of the 

 two elementary signs, we have at our command 



2 + 4 + 8+ 16 = 30 



variations for the formation of an alphabet. 



These- variations, with some others, have been disposed as 

 follows : 



Letter. 



A 

 A 

 B 

 C 

 D 

 E 

 $ 

 F 

 G 

 H 

 I 



Sign. 



I. ALPHABET. 



Letter. 

 J 



K 

 L 

 M 



9 



o 



6 

 p 

 Q 

 B, 



S 



Sign. 



