HISTORY AND PROGRESS. 



33 



which the leading wires from the receiving station were 



connected. The contact springs to which the ends of the 



wire coils were attached travelled in 



the white annular spaces, and made 



contact only at a and b, whilst in 



every other position the circuit was 



interrupted. 



The receiving apparatus consisted 

 of an oblong coil of wire or multiplier 

 of 600 turns, in the centre of which Fig. 15. 



were supported, on vertical axes, two magnetic needles, 

 their neighbouring ends having opposite magnetic polarity. 

 Fig. 16 gives a vertical, and Fig. 17 a horizontal section 

 of this instrument, a b is the coil of wire, N s and N s, 

 the magnet needles, turning on the axes m and m', and 



m Fig. 16. 



carrying on their neighbouring ends brass continuations with 

 small ink reservoirs, c c'. These reservoirs were furnished 

 with capillary tubes and filled with printer's ink, so that on 

 coming in contact with the strip of paper travelling before 

 them they each printed a dot. Two plates, h h', prevented 

 the needles from being deflected in the direction opposite to 

 that in which they were to print, as the deflection by the 

 current would otherwise have caused them to swing, and 

 perhaps mark the paper, not only when responding to signals, 

 but also when oscillating. 



D 



