“366 : poeel&r. science^ review; j/...; .; 
then so soon as the conducting circuit is rendered entire by 
putting the wire to “earth,” there the current will flow from 
Falmouth along the wire to Lisbon, just as if the earth itself had 
led the current back to the zinc plate. On the other hand, if 
the copper plate be earthed and the zinc plate be connected by 
wire to Lisbon, where it is “earthed,” just the reverse will 
take place, and the current will seem to flow from England to 
Lisbon through the earth, and will return to England by the 
wire. The sender at Falmouth connects the first zinc and last 
copper plate of his battery to a “ signalling key,” which is an 
arrangement for enabling him, by simply pressing down one or 
-other of the two levers like piano keys, to control the battery 
-so that (he can apply the zinc plate or pole of the battery to 
■•“earth” and the copper pole to the cable, or vice versa , for any 
length of time he chooses. The receiver at Lisbon sets the 
“ mouse-mill” running, and by a battery, also joined up “in 
series,” magnetises the electro-magnets of the recorder. He 
connects the cable by means of the wire to the moveable 
coil, and the coil by the other wire to the earth ; and so com- 
pletes the conducting circuit between the zinc and copper poles 
of the sender’s battery at Falmouth. Then, when the paper 
is running and the ink .squirting so as to mark a straight line 
upon it, the instrument is ready to record the message from 
Falmouth. The sender there controls the electricity by means 
of the key according to a code of signals. The code uni- 
versally adopted now is the Morse code, so called after the 
inventor. The fundamental basis of this code is two ele- 
mentary signals, usually called the dot and dash. Every letter 
of the alphabet is made up of one or more of these signals. 
In the application of the Morse code to the recorder it 
is arranged that a dot and dash is transmitted when the sender 
presses the left and right-hand levers of the key respectively, 
just as in the case of the “needle instrument,” and a dot is 
recorded by a motion of the siphon point towards the coil ; 
and the paper being in motion, the ink traces out a small wave, 
while a dash is recorded by a wave on the opposite side of the 
axis of the paper. 
The message being composed of a combination of such waves, 
with short intervals between each letter and longer intervals 
between each word, during which the siphon marks a straight 
line up the middle of the paper, presents a very serrated and, 
to the uninitiated, very unintelligible appearance, but an expert 
clerk can translate it as fast as ordinary handwriting. 
There are of course various contractions for words conven- 
tionally employed, which facilitate communication in electric 
telegraphy, but without the aid of any of these, and by the 
use of an automatic sender — -for _ few clerks can send 
