62 On the Electric Telegraph of Prof. Morse. 
ent” circuits are described. 'The first consisting of a single wire 
and the ground. The wire broken by keys and the receiving 
operator, keeping the circuit closed, and breaking or closing at 
pleasure—such is the circuit always employed, for the various 
reasons already alluded to. The way in which this single wire 
is introduced at the stations may be understood from the diagram, 
(fig. 5,) and illustrated by the supposition of a break. When at 
Fig. 5. 
A 
an intermediate office the line is found deranged from the evi- 
of a current unnaturally strong or weak, or from the entire 
want of a current, the inference is that the wire is broken on one 
or both sides of the office. Supposing the wire continuous from 
one terminus of the line to the other, and a battery at each, the cur- 
rent passes through the intermediate magnet without interruption, 
and the circuit established is termed a “through circuit.” Now 
a derangement existing, the intermediate operator alters this 
“throtigh circuit,” and by connecting with the ground, makes 
two “short circuits.” If the line is broken only on one side, a 
current is at once obtained from the battery of the unbroken side, 
and the arrangements for repair are guided accordingly. 
diagram exhibits a means of instantly applying this test, as also a 
convenient method of dividing a long line into sections as the 
business may demand. The black dots A, B, C, D, represent 
brass terminations of conducting wires, sunk toa level with the 
surface of the operator’s table ; over their surface a metallic button 
plays, (Fig. 6.) ‘This button connects each brass Fe i 
stud with its opposite, and a change in its position : 
changes the direction and channel of the current at 
pleasure. Thus the intermediate operator wishes 
to break and close the “through circuit.” He 
turns his button bringing B in connection with 
~ D. The course of the current can be easily traced. But 
again, cutting off his left-hand neighbor, he wishes to corres- 
with the right, the button, changed so as to connect A 
with 'C, the current passes directly to the ground through his 
instruments. Supposing a binding screw at S, the left or ot 
hand wire may thus be brought in connection with 
ground. ‘The buttons 1, 2 and 3, are simply used as- jot od 
ient duplicate keys, or circuit closers, when the operator is receiv- 
a 
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