ositive polarity through the receiving
paper and stylus in the reverse direction and through the line, L, which
returns to the negative pole of the battery by way of the artificial
resistances, R and R'. Such an impulse, following immediately upon the
interruption of the circuit of the transmitting battery, acts to destroy
the effect of the "tailing" or static discharge of the line, L, upon the
receiving instrument, and also to neutralize the same throughout the
line. By thus opposing the discharge of the line by a reverse current
transmitted directly through the chemical paper, a sharply defined
record will in all cases be obtained; and by transmitting the opposing
impulse through the line, the latter will be placed in a condition to
receive the next succeeding impulse and to record the same as a sharply
defined character.

This arrangement was made on the New York-Cleveland circuit, and the
characters were then clearly defined and of uniform distinctness. The
speed of transmission on this circuit was from 1,000 to 2,000 words per
minute.

Upon the completion of the wire to Chicago, total distance 1,050 miles,
including six miles of No. 8 iron wire through the city, the maximum
speed was found to be 1,200 words per minute, and to my surprise the
speed was not affected by the substitution of an underground conductor
for the overhead wire.

The underground conductor was a No. 16 copper wire weighing 67 pounds
per mile, in a Patterson cable laid through an iron pipe.

I used 150 cells of large Fuller battery on the New York-Chicago
circuit, and afterward with 200 cells in first class condition,
transmitted 1,500 words, or 37,000 impulses, per minute from 49
Broadway, New York, to our test office at Thirty-ninth Street, Chicago.

The matter was always carefully counted, and the utmost care taken to
obtain correct figures.

It may be mentioned as a curious fact that we not only send 1,200 words
per minute through 1,050 miles of overhead wire and five miles of
underground cable, but also through a second conductor in No. 2 cable
back to Thirty-ninth Street, and then connected to a third underground
conductor in No. 1 cable back to Chicago main office, in all about
fifteen miles of underground, through which we sent 1,200 words per
minute and had a splendid margin.--_Electrical World_.

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[ELECTRICAL REVIEW].

THEORY OF THE ACTION OF THE CARBON MICROPHONE--WHAT IS IT?