combination with other systems led to the present 

 printing telegraph system. 



The high speed of transmission of the Baudot 

 system was largely due to the replacement of the 

 Morse code by an older one, the 5-unit code, which 

 had originally been used in the Gauss-Weber and 

 the Wheatstone-Cooke telegraph systems. In the 

 5-unit code each signal was formed by the proper 

 combination of five plus or minus currents. The 

 correct combination of currents was created by 

 depressing the appropriate jacks on a keyboard 

 equipped with five keys. There was one keyboard at 

 each transmitting station, and a number of these sta- 

 tions were connected to the commutator. The com- 

 mutator, as in Farmer's suggestion, connected each 

 keyboard in succession to the line. Usually four key- 

 boards were used; if so, there were four main seg- 

 ments on the commutator, with one segment for each 

 keyboard. Each segment was further subdivided with 

 one subdivision for each key of the keyboard corre- 

 sponding to that segment. As the brush on the com- 

 mutator moved over the segments, each key of a given 

 keyboard was connected in succession to the line. An 



FiGUBLE 43. — Top: American lineman of the mid-igth century. 

 Bottom: Construction of a telegraph line across the Missouri 

 River in 1851. From T. ShafFner, The Telegraph Manual, New 

 York, 1859, pp. 542, 666. 



PAPER 29: DEVELOPMENT OF ELECTRICAL TECHNOLOGY IN THE 19TH CENTURY: II 



309 



