SP. Langley—Allegheny System of Time Signals. 385 
tant cities, such as Chicago or Philadelphia, can be reached 
only by the wires of the telegraph or railroad companies, which 
are too valuable to be exclusively employed for this purpose. 
The method used on the Pennsylvania Central, and Pittsburgh, 
Fort Wayne and Chicago roads, will sufficiently illustrate the 
System as applied to railways. 
A special wire connects the observatory with the office in 
which the wires owned by these roads unite. In this office is 
asmall bell which is struck lightly every second, in the manner 
escribed, and except for the pauses to designate the minute 
and hour, continues to sound unintermittingly ; affording to the 
conductors and other employees specially concerned in the time 
ameans of ready comparison, even without entering the building. 
At 9 and at 4, Altoona time (ten minutes fast of Pittsburgh), 
the Pittsburgh operator in charge connects the main eastern wire 
to Philadelphia, 354 miles distant, with the observatory, and for 
the ensuing five minutes the beats of the Howard mean-time 
standard are automatically repeated on similar bells, or on the 
customary ‘“sounders” in Philadelphia and in every tele- 
graph office through which the road wire passes; all station 
clocks and conductor's watches being compared with it as the 
Official standard. After five minutes the clock is “switched” 
by the Pittsburgh operator out of the main line wire, which is 
returned to its ordinary use. 
A similar set of signals, lasting for five minutes, is sent at 9 
and 4 of Columbus time (18 minutes slow of Pittsburgh) to all 
Stations as far west as Chicago inclusive, in the main western 
line (of 468 miles in length). At Philadelphia the time is 
6 
for using a single unit of time, as, though the names of “ Phila- 
delphia time,” “ Altoona” or “Col i 
n 
train, is regulated from a single standard, that of the clock in 
the observatory. 
The advantages of this uniform and wide distribution of ex- 
act time in facilitating the transportation of the country, and in 
enhancing the safety of life and of merchandize in transit be- 
tween the Western and the Atlantic cities seem to be suffi- 
Clently evident. The fact that the system, described in this 
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article, has obtained the extension it has, within three years 
