concerned "family affairs." In other words, the
main use of the telegraph was to send time-sensitive information between the Stock Exchange and other parts of the country.
As a result, the telegraph link between the Stock Exchange branch office and the Central Telegraph Office, a distance of 220
yards, carried more messages than any other part of the network; and the value of these messages depended on their being delivered
swiftly.
Josiah Latimer Clark, who worked as an engineer for the Electric Telegraph Company (and who later carried out the experiment
that disproved Whitehouse's theories about transatlantic telegraphy), applied himself to the problem and came up with a radical
solution. He proposed a steam-powered pneumatic tube system to carry telegraph forms the short distance from the Stock Exchange
to the main telegraph office. Since outgoing messages would be carried by tube, the telegraph wire along the route could be
dedicated to incoming messages, and the level of traffic along the wire would be dramatically reduced.
Clark first tested the idea in 1853, and by 1854 an airtight tube an inch and a half in diameter had been laid underground
between the two telegraph stations. It was capable of carrying up to five messages at once, written on telegraph forms and
stuffed into a cylindrical carrier made of the ever-useful gutta-percha. Each carrier had a felt pad at the front end to act
as a buffer, and was covered with leather to prevent the gutta-percha from melting, since friction with the inside of the
tube tended to make the carriers, moving at twenty feet per second, very hot. A six-horsepower steam engine in the basement
of the Central Telegraph Office created a partial vacuum in front of the carrier, and it took about half a minute to draw
each one down the tube from the Stock Exchange. Even when the carriers were not fully loaded, this system was much faster
than sending the messages by telegraph, which could only send about one message per minute. Once a carrier arrived at the
Central Telegraph Office, the forms were unloaded and the messages telegraphed to their destinations in the usual way. The
original tube was one-way only, since the vast majority of messages originated at the Stock Exchange end. Batches of empty
carriers were taken back to the Stock Exchange by messenger.
This first pneumatic tube was far from perfect, and carriers frequently got stuck, but the company was convinced of the benefits
and introduced a second underground tube in 1858. With a larger bore (two and a quarter inches) and running nearly a mile
from another branch office, in Mincing Lane, to the central office, this improved tube was operated by a more powerful twenty-horsepower
steam engine. It proved successful enough that after a while the company decided to make this tube two-way.
So that steam engines would not be needed at both ends, a "vacuum reservoir," consisting of an airtight, lead-covered box,
ten by twelve by fourteen feet, was constructed in the basement of a house in Mincing Lane. However, one day a carrier got
stuck in the tube, causing the pressure in the vacuum reservoir to drop, until eventually it imploded with a loud bang, demolishing
the wall between it and a nearby house. According to a contemporary report, "At the time the landlord of the house happened
to be dining in the next room, and he suddenly found himself, his table, his dinner, and the door, which was wrenched off
its hinges, precipitated into the room amongst the debris of the chamber." Following this accident, carriers were sent by
pushing them along the tubes with compressed air, rather than drawing them along with a partial vacuum.
By 1865, the increase in traffic had led the Electric Telegraph Company to extend its London tube network and install tube
systems in Liverpool, Birmingham, and Manchester. Similar systems were initiated in Berlin in 1865 and Paris in 1866, and
before long
main use of the telegraph was to send time-sensitive information between the Stock Exchange and other parts of the country.
As a result, the telegraph link between the Stock Exchange branch office and the Central Telegraph Office, a distance of 220
yards, carried more messages than any other part of the network; and the value of these messages depended on their being delivered
swiftly.
Josiah Latimer Clark, who worked as an engineer for the Electric Telegraph Company (and who later carried out the experiment
that disproved Whitehouse's theories about transatlantic telegraphy), applied himself to the problem and came up with a radical
solution. He proposed a steam-powered pneumatic tube system to carry telegraph forms the short distance from the Stock Exchange
to the main telegraph office. Since outgoing messages would be carried by tube, the telegraph wire along the route could be
dedicated to incoming messages, and the level of traffic along the wire would be dramatically reduced.
Clark first tested the idea in 1853, and by 1854 an airtight tube an inch and a half in diameter had been laid underground
between the two telegraph stations. It was capable of carrying up to five messages at once, written on telegraph forms and
stuffed into a cylindrical carrier made of the ever-useful gutta-percha. Each carrier had a felt pad at the front end to act
as a buffer, and was covered with leather to prevent the gutta-percha from melting, since friction with the inside of the
tube tended to make the carriers, moving at twenty feet per second, very hot. A six-horsepower steam engine in the basement
of the Central Telegraph Office created a partial vacuum in front of the carrier, and it took about half a minute to draw
each one down the tube from the Stock Exchange. Even when the carriers were not fully loaded, this system was much faster
than sending the messages by telegraph, which could only send about one message per minute. Once a carrier arrived at the
Central Telegraph Office, the forms were unloaded and the messages telegraphed to their destinations in the usual way. The
original tube was one-way only, since the vast majority of messages originated at the Stock Exchange end. Batches of empty
carriers were taken back to the Stock Exchange by messenger.
This first pneumatic tube was far from perfect, and carriers frequently got stuck, but the company was convinced of the benefits
and introduced a second underground tube in 1858. With a larger bore (two and a quarter inches) and running nearly a mile
from another branch office, in Mincing Lane, to the central office, this improved tube was operated by a more powerful twenty-horsepower
steam engine. It proved successful enough that after a while the company decided to make this tube two-way.
So that steam engines would not be needed at both ends, a "vacuum reservoir," consisting of an airtight, lead-covered box,
ten by twelve by fourteen feet, was constructed in the basement of a house in Mincing Lane. However, one day a carrier got
stuck in the tube, causing the pressure in the vacuum reservoir to drop, until eventually it imploded with a loud bang, demolishing
the wall between it and a nearby house. According to a contemporary report, "At the time the landlord of the house happened
to be dining in the next room, and he suddenly found himself, his table, his dinner, and the door, which was wrenched off
its hinges, precipitated into the room amongst the debris of the chamber." Following this accident, carriers were sent by
pushing them along the tubes with compressed air, rather than drawing them along with a partial vacuum.
By 1865, the increase in traffic had led the Electric Telegraph Company to extend its London tube network and install tube
systems in Liverpool, Birmingham, and Manchester. Similar systems were initiated in Berlin in 1865 and Paris in 1866, and
before long
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