34 THE ELECTRIC TELEGRAPH. 



By means of the plates, therefore, a current sent through 

 the coil deflected only one of the needles at a time, the 

 other being held back ; and on the current being changed, 

 the reverse took place the other needle only being 

 deflected. Thus the signals on the paper were recorded in 

 two lines those to the right marking the deflections in 

 that direction, and those on the left indicating the left hand 

 deflections. A paper strip was kept in uniform motion by 

 means of clockwork, which, whenever a mark was made, 

 moved the paper onwards, leaving a blank space before 

 the next signal. These signals were necessarily only dots, 

 because induction currents are only of momentary duration. 



Much nicety was required in obtaining magnets of exactly 

 the right size. They could not, for example, be large, 

 because their inertia would have been too great ; nor too 

 small, because their mechanical force would not have been 

 great enough to have effected the printing. Two small per- 

 manent magnets in the rear of the printing needles retarded 

 their inclination to be deflected when not under the influence 

 of currents. The letters of the alphabet were constructed 

 from combinations of, at most, four of the dots given in suc- 

 cession by the pointers of the two printing needles. They 

 were arranged by Steinheil as follows : 



A ..... .% L ---- .. ---- ... 



"R M 1 



* . . . . j. . . , 



C,K . . .. 1ST .,.. 2 . . . . .* 



D . . . . O . . . . 3 .... t 



E . . . . P . . . . .. 4 .... . 



F ..... E . . . . .. 5 .... ... 



G ..... 8 .... .. 6 .... ... 



TT T 7 



J. . . , . . ' 



Ch. ....... TJ.V..V 8........ 



ScL W Q 



kJL-Jl ' .. TT ** i/....' rw _ 



J . . . . Z . . . . .. 



