Get him on the Blower!: The origins of Pneumatic Railways

Telegraphs were the internet of the Victorian Age. News of political and business developments could be sent around the world in near real time. However, the mass of telegrams converging on the network hub in London was becoming a bandwidth problem, with messages lagging hours to cross London to be delivered to the appropriate department or company by courier. The solution, ironically, was air.

Britain’s first telegraph line from Paddington to Slough made headlines in 1844 when it transmitted the news of the birth of Queen Victoria’s second son Prince Alfred at Windsor, to London. But it was several years before this technology would catch on outside the railways (which used them to pass train running information along the line). After being exhibited in the Great Exhibition of 1851, telegraph use took off in Britain, providing London with near-instant communication with other cities. Once the first telegraph submarine cable linked England and France and other parts of Europe in 1852, London was connected near-instantly with its neighbouring countries. Telegraphy exploded following the similar exponential network growth curve that steam railways had just experienced. As about half of the telegrams were for stock and commodity prices, and a further third being business related (the remainder were to do with personal or family matters, telegraphy was rapidly changing the nature of society. The electric telegraph enabled the globalisation of financial markets. For the first time, financial developments in the Empire or on Wall Street were felt immediately, not subject to the delay whilst a steamer traversed the oceans over weeks. Tom Standage’s excellent book The Victorian Internet describes this impact in readable detail, highlighting the many communications network concepts that are familiar to us today thanks to the internet.

However, as the popularity and volume of telegraph messages increased, many telegraphy companies established branch offices around central London to assist in collecting and distributing telegram communications. But telegraph offices in London were becoming inundated by telegrams during the day, causing backlogs. And whilst telegram messages travelled at great speed between cities, forwarding them on the heavily crowded streets of London via messengers could take hours and sometimes over a day. Hiring more skilled & costly telegraph operators to re-transmit telegrams locally was not seen as cost effective at all, as they were often idle at branch offices.

A pneumatic solution

Surprisingly, it was a non-electric pneumatic tube concept, designed and constructed by engineer J Latimer Clark, which sent the amassed paper telegrams more cheaply and quickly within cities themselves. Clark built the world’s first practical tube that carried messages in carriers in 1853, between the Electric and International Telegraph Company headquarters (called the Central Telegraph Station) on Telegraph Street in Lothbury and their offices at the Stock Exchange on Threadneedle Street. Half of all telegrams in London were being sent between these two offices.

The original single tube line was 1½ inch in diameter, with messages first conveyed in felt bags pulled by the air vacuum generated by a 6 horse power (hp) steam engine. Telegrams were sent from the Stock Exchange 675 ft. to the Central Telegraph Station, with the carriers being returned by hand.

However the felt bags were not terribly durable. All manner of carrier construction and material was tried – leather, vulcanised fibre, celluloid, aluminium, and brass. By much experimentation it was determined that carriers made of gutta-percha (an early kind of plastic made from the latex of a Far East tree species) with an outer lining of felt or leather for less friction were the most robust. The diameter of the cylinder was slightly smaller than that of the tube to enable it to traverse bends, and had a felt skirt to provide the air seal. Being the pioneering installation, there were problems with carriers getting stuck, especially in curves, but these issues were progressively worked through. The engine pulled the carrier with up to six telegrams the distance in 30 seconds, half the time it took to send an average single telegram.

Pneumatic advantages

Pneumatic tubes (or telegraph tubes as they were also known) saved cost because they did not require skilled, well-paid telegraph operators, and they eliminated mistakes that often occurred in telegraph re-transmission. Pushing a carrier into a pipe requires much less skill. There was also no error in transcription, which was a frequent occurrence, and cash, documents and other small objects could also be conveyed securely. As telegrams could be sent in a pneumatic tube carrier faster and cheaper than the post or by messenger, it is perhaps no surprise they soon became a popular method of communication.

Expanded pneumatics

The next tube, the Electric and International Telegraph Company built, in 1858, was over ten times longer at 3,120 ft. Powered by a much bigger 20hp engine and using a larger 2¼ inch diameter tube for greater message capacity, it linked up another office in Mincing Lane, just west of Fenchurch Street station.

In 1860 the Electric and International Telegraph Company systems linked their new, larger Lothbury central office with a station at Cornhill near the Bank of England. Many other pneumatic tube lines were soon installed radiating out from this office, laid in pairs, one up and one down.

The former headquarters of the Electric & International Telegraph Company (known as the ‘Electric’) near the GPO was used until the Central Telegraph Office moved there in 1874, (The English & Irish Magnetic Telegraph Company being known as the ‘Magnetic’).

Busier lines were built with 3 inch diameter tubing, such as the Messrs. Siemens Bros. line installed for the Post Office under the streets between the Central Telegraph Station and the General Post Office (GPO). It was completed in 1870, and was soon extended to Fleet Street and Charing Cross.

Telegraph nationalisation

Several private telegraph companies handled telegraphy, but given the importance that telegraphy communications was starting to have, the government in 1868 passed the Telegraphs Act to nationalise inland telegraph companies and incorporate these communications within the Post Office. This is a rare case of the laissez faire economic policies of the era being set aside for national interests, and demonstrates the key role that the government viewed for the new communication medium.

State acquisition was made in combination with a standard one shilling for 20 words inland rate telegram, and introduction of telegram services to Post Office branches throughout the country. This greatly increased the reach of telegraph communications, and required a number of new pneumatic tubes to be installed in London.

Central Telegraph Office – It’s quicker by tube!

Indeed the success and growth of telegraphy meant that the Electric’s Telegraph Street office had become grossly overcrowded by the time of nationalisation, and so the new Post Office begain construction of a new building to act as their new Central Telegraph Office (CTO). This was completed in 1874, with the Post Office persuading the City to rename Bell Alley, on which the CTO was sited, to “Telegraph Street.” The CTO was designed to be the hub of both the British telegraph network and the London pneumatic tube network. The latter simplified work at branch offices, as well as expediting communications at GPO West itself, the official (albeit rarely used) name for the CTO.

In fact it is fair to say that the CTO could not function without its own extensive in-house tube system, which initially was comprised of 12 tubes. Even telegrams transferred on the same floor went via the tubes for more efficiency, which avoided the confusion of messengers gathering around the message-sorting and routing desks.

The first online community, & the inevitable privacy concerns

Telegraph operators formed an exclusive but unofficial community, closed to themselves, the world’s first online community. They observed a strict hierarchy, as befitting the British class structure, that developed from the fact that the fastest and best operators worked in London at the busiest offices, with slower, less accurate ones working progressively further out. Furthermore, operators had their own lingo and secrets. This caused concern for the businesses using telegraphs over the privacy of the messages.

Given that half the messages were sent by businesses, and many of those concerned stock and commodity prices, pneumatic messages were faster, more secure and more reliable than telegrams within cities. Telegrams were often forwarded on from station to station numerous times to reach their destination, and thus were seen by many eyes. Hence business and government readily took to the more secure pneumatic tubes as this reduced the number of individuals who read their messages.

Eventually, nearly all branch telegraph offices were connected directly to the CTO via pneumatic tubes, but with only a few intermediate stations. The Post Office Engineer-in-Chief calculated that trunk 3 inch tubes, with cylinders carrying up to 55 telegrams that could be sent every 10 to 30 seconds (depending on the distance), was the equivalent of seven telegraph wires and 14 operators working at peak efficiency.

Critical communications

Furthermore, most carriers were not sent full, so the tubes handled message surges much better than the serial telegraphy system. This was demonstrated during the run-up to, and events of, the Franco-Prussian War which broke out in July 1870. This threatened to (and did) destabilise the European balance of power which had lasted since 1815. So pneumatic tubes were a critical part of London’s, the country’s, and the Empire’s economic and government communications network.

By 1875, the CTO had 450 telegraphic instruments on three floors, linked by 68 pneumatic house tubes in a highly integrated system. The longest internal tube transit time was only 10 seconds. The London system grew steadily and the Post Office had at one point 11 miles of house tubes and 74 miles of street tubes, connecting cable companies, branch offices, two railway termini, a bank, and three newspapers on Fleet Street. By 1891, over 32 million telegrams a year were being sent world-wide. Half of which were sent in the United Kingdom, with half of those passing via the CTO in London.

Indeed such was the continued growth of communications that a fourth storey was added to the CTO only 10 years after its construction, enlarged twice in 1901 and 1902, then a fifth storey added in 1930. At its busiest it had a staff of 5,000 working around the clock, connecting all corners of the Empire as part of what became known as the ‘All Red Line’.

This was the informal name for the network of telegraph lines that connected London with the Empire, so named because on many political maps, the British Empire was coloured red. The government felt the All Red system should land only on British controlled soil for security purposes, and the network was designed with so many redundancies such that 49 cuts would be needed to isolate the United Kingdom.

The 1911 Committee on Imperial Defence report stated that the Imperial Wireless Chain should only be a reserve to the All Red Line, because enemies could interrupt or intercept radio messages. Despite its great cost (£2 million at the time) the telegraph network succeeded – British communications remained secure and uninterrupted during World War I, whilst Britain quickly succeeded in cutting Germany’s worldwide communications network.

Pneumatic tubes spread to other cities

After London’s pioneering development, similar systems were installed in the provinces, starting in 1864 in Liverpool. This system was also the first in which messages could be sent in both directions: carriers were propelled by compressed air in one direction, and a vacuum in the other. This technique became common for use on systems with lower volumes.

London’s successful pneumatic tubes soon spawned similar systems in Berlin (1865), Paris (1866), and Vienna (1867), followed by most major European and US cities. By the 1870’s similar systems were operating in every modern major city of the world.

Pneumatic communications were seen as being the next big technology, following steam traction and the electric telegraph. Jules Verne’s Paris in the Twentieth Century of 1863 included pneumatic tube trains that stretched across oceans. His later The Day of an American Journalist in 2889 depicted submarine pneumatic tubes carrying people faster than aeroplanes, due to the vacuum providing less friction.

Eventually, Paris developed a more intensive pneumatic network that operated more like an express post, allowing their distinctive bleu envelopes to be mailed from mail boxes, post offices, and even from boxes mounted on the rear of trams, to be unloaded at the end of the line.

Refining the technology

By 1874, an extensive system of telegram tubes was in place in London, linking the Central Telegraph Office on St. Martin’s le Grand with London’s district post offices, distributing around 4.5 million messages annually. By 1886, London had 94 telegram tubes totalling 34½ miles, powered by four 50 hp. engines, connected to 70 Post Office branches. Several tubes remained privately-owned at that time and were leased by the GPO. Businesses and individuals could simplify addressing of telegrams by purchasing and renewing a unique one word telegraphic address, that would enable the sender to omit (or forget) the full postal address. An example is ‘SCOPO’, for a patent law firm near Chancery Lane. As such telegraphic addresses can be seen as forerunners of today’s internet domains and email addresses – a simple way to find and contact a company or individual.

Pneumatic tube types

Three types of pneumatic tube systems were eventually implemented: street, house. and ticket tubes Related but simpler voice tubes were also used.

Street tubes

Street tubes were made of lead, laid within iron ducts for protection one to two feet under the street between branch post offices to the CTO (from whence they were telegraphed). Most tubes were 2½ inches in diameter, with 3 inch diameter tubes being used for heavily trafficked lines. There were a few light 1½ inch tubes which carried 5 telegrams per carrier, whilst the 2½ inch carriers could hold 30 messages, and the largest held up to 55. The carriers reached an average speed of 30 feet per second or 20mph and could be dispatched every few seconds in short tubes or every 30 or 40 seconds in long tubes. Street tubes required pressures of up to 12 lb. per sq. inch above ambient. By the 1930’s, two electric compressors replaced steam engines to power all of the street tubes in London.

House tubes

Pneumatic systems built between different parts of the same or adjoining buildings were called ‘house tubes’. Usually 1.5 inch diameter, they were installed and used in a great number of private and government offices. In Post Office branch offices, house tubes were also installed to pass telegrams from the public counter to the instrument room. House tubes ran in loops, to allow external messages to both be sent and received, as well as handling internal communications.

As mentioned above, house tubes were soon installed in telegraph offices themselves to pass messages more quickly and efficiently between the hundreds of workers. In 1875 the CTO had 450 telegraph instruments on three floors, grouped by Metropolitan, Provincial, and International lines, all interconnected by 68 house tubes for transferring messages and tracking charges. House tubes were also later installed in some telephone exchanges for sending fault dockets from test desks and switchrooms to apparatus rooms.

Shorter house tubes were powered by hand pump (when the tubes were short and the traffic light), necessitating physically fit men, vetted before hiring by the company doctor. Later some house tubes were supplanted by electric power.

It was estimated that over one hundred house tubes were in use in London, in post offices, telegraph, and telephone exchanges, as well as later on in department and large stores for secure cash handling.

Pneumatic tube systems were also installed in larger Royal Navy ships such as battleships and aircraft carriers, connecting the wireless telegraphy (as it was called in the Navy), the bridge, the engine room, and other parts of the ship, as one of numerous communications systems for redundancy.

Ticket tubes

Telephone systems were introduced slowly from the early 1880’s, and although capable of much greater bandwidth than telegraph, the two forms co-existed, and were still supplemented by pneumatic communication. Specifically, pneumatic ticket tubes were installed in telephone exchanges to book and forward telephone calls.

The first Post Office ticket tube installation was in the London Trunk Exchange in GPO South, Carter Lane, EC1 in 1911. The tubes were of a slim rectangular design, 2 5/8″ x 3/8″, and dispensed with the carrier altogether, using instead hard paper dockets that were written on, bent up to form a sail, then blown through to set up and route calls. Once the call was placed, the docket was then sent with the time and duration of the call to the accounting office to record the call’s charge. Ticket tubes also conveyed fault dockets between switchboards and the apparatus rooms. Several dockets could be sent in quick succession, typically 12 per minute; more was possible but at a higher risk of blockage. The average number sent in a day was 15,000. The Post Office estimated that this system saved five operators. By the 1930s with the rapid growth of the telephone network, hundreds more ticket tubes were installed in GPO South.

Voicepipes and speaking tubes

Steam powered ships were much noisier and larger than their sail powered predecessors,which meant that traditional shouting of navigational commands no longer worked. Scientific American of May 1897 wrote:

A form of speaking tube for use of steamers has recently been introduced in England. The peculiarity of it lies in the fact that the pipe is insulated from the body of the ship by a covering of waterproof textile material. This latter, being a very bad conductor of sound, enables long lengths of tube to be used without rendering the speech transmitted inaudible at the far end. The distance from the bridge to the engine room on the steamer India is over 300 feet, yet even with the engines running it is possible to hear clearly in the engine room, through the tube there fitted, orders given on the bridge. An electric call is fitted, as the ordinary whistle cannot be used for so long a length of pipe.

Shipboard electric telephones were still a couple decades in the future, so a simple version of tubes were developed as voice pipes in the 1890s (again by the British) to provide shipboard communications. The maritime term was voicepipe, whilst those on land were called speaking-tubes. Systems typically had a removable whistle plugged into each end, to be blown from the other end to announce impending communication, hence the expression “I’ll get him on the blower”. Some longer voicepipes had an electric buzzer and wire installed alongside to signal the desire to communicate.

Shipborne voicepipes had to compete with the noise of machinery and weather, which is why they had a larger diameter than speaking tubes. Acoustic losses in a tube are due to viscous friction between the vibrating air and the walls of the tube. On doubling the tube diameter, the wall area for a given length is also doubled, but the mass of air in that length is quadrupled, thus a bigger tube has lower sound loss. Increasing the diameter of the pipes, however, would decrease the intelligibility of human speech, due to the relationship between the frequencies of typical speech and the frequencies of sound attenuated within the larger tube. The attenuation effect of the voicepipe tube on the voice can be heard on the Beatles’ song ‘Yellow Submarine’.

Early open cockpit aeroplanes, where wind and engine noise made normal speech between pilot and observer/navigator/gunner impossible, also had voicepipes.

Terrestrial speaking tubes in contrast generally had shorter pipe runs in a relatively quieter environment, so had smaller 1-2 inch diameter tubing than the sea-going version. These were also easier to conceal in walls and under floors, and didn’t require acoustic insulation. They were used in offices to connect different departments, in affluent houses to contact servants, and in expensive cars to speak with the chauffeur.

Wire pulley & conveyor house systems

Wire carriers with baskets, cash balls, miniature cash railways, multiple-wire, and band conveyors were also installed within and between rooms of larger telegraph offices for transferring messages for onward transmission. Wire carrier and cash ball systems were installed in stores for the delivery of cash, bills, and small merchandise items.

The result was Victorian engineering deluxe, and part of the modern retro-Victorian steampunk’s delight of telegraphs, pneumatic tubes, telephone tubes, and overhead wire baskets shuttling messages overhead, underfloor, and through walls hither and thither to expedite messages, as part of a well-engineered information and message processing and routing centre.

Pneumatic tubes in the Twentieth Century

The CTO, with its pneumatic tubes still working but its telegraphs augmented by a telephone network, was still considered the communications hub of the country and Empire into the mid-twentieth century. So important was it still to the British economy that it was deliberately and successfully targeted by the Luftwaffe in World War II, badly damaging it in December 1940, which affected the pneumatic tube network as well. Fortunately seven of the street tubes were transferred to the reserve King Edward Post Office building nearby within the year. The full tube network was restored after the war along with the rebuilt CTO.

Government’s own pneumatic tube network

Up to 1859, the British Foreign Office had to send telegrams to the telegraph office like any other individual or company. In 1878 London’s longest street tube section of four 3 inch tubes was completed, connecting the House of Commons and the CTO, with an intermediate station at West Strand, a distance of 2 miles 353 yards. Two tubes went via the Strand and two via Bazelgette’s Embankment. At the same time, the Post Office took advantage of the street excavation to lay revenue earning pneumatic tubes for newspaper companies along Fleet Street.

By 1870, telegraph lines were installed at the Foreign and Colonial Offices, and submarine cables were starting to reach most continents. This effectively centralised Empire power and decision making in London. No longer were commanders and governors in the field allowed to take the initiative in making decisions, being weeks or months away from London. Dispatches, reports, and decisions could be sent around the world in minutes.

A self-contained government-only pneumatic tube network connecting offices all along Whitehall, with its hub in the basement of the War Office, was started in 1918. It ran between the House of Commons and the Press Bureau in Whitehall with the Press Bureau terminal, and connected to the Central Telegraph Office. By World War II the government tubes sub-system had been expanded to connect 10 Downing Street, the Cabinet War Office, the Admiralty and the Home Office, to the Foreign Office, the Colonial Office, the India Office, the Treasury, and several branch telegraph offices.

Wartime pneumatic tubes

A separate 13 by 5 inch rectangular tube system for document box files was built between the War Office, the Montagu underground bunker, Quarter Master General House, and Metropole which transported 50,000 documents a day. The total cost of the government sub-centre network was about £60,000, but was deemed to have saved thousands of pounds a year in communication costs, with unknown thousands more in the more expeditious handling of events.

The Goodge Street North Deep Shelter, in its role as the World War 2 Supreme Allied Command Headquarters, was also connected by a Lamson street pneumatic tube system to Churchill’s Cabinet War Rooms under Whitehall. Lamson was the premiere British pneumatic tube company starting around 1900. The tube terminals can still be seen by the public in the Cabinet War Rooms.

Telephone cable tunnels had also been dug between various government buildings by 1940, but despite this, the pneumatic tubes were still intensively used for sending documents, plans, and maps.

It is not known how long these government tubes were used after the war, but some may still be in service today, as they are secure, remotely unjammable, and not susceptible to electronic eavesdropping or electro-magnetic interference.

The book The Official History of Britain and the European Community writes of a pneumatic tube system which ran between 10 Downing St and the Foreign Office as recently as 2003. Peter Stothard’s Thirty Days: An Inside Account of Tony Blair at War describes the underground Foreign Office in operation:

A young team of shift-workers, operating both encrypted computers and antique compressed-air communication tubes, gathers intelligence, turns it into memoranda and tries to make sure that the right people read it.

There was also a house tube system in the House of Commons, which may still be operational.

The post-war Post Office pneumatic tube network

In 1957 the CTO street tube network was still quite large, even though it carried only 10,000 telegrams a day versus the 50,000 a day in 1909. At that time it still connected:

• 40 Post Office district and branch offices
• 2 Postal Sorting Offices
• 3 Post Office service departments
• 1 Post Office accounting department
• 2 railway station post offices
• 3 newspaper publishers
• 1 bank
• 3 cable companies
• War Office sub-centre of 6 offices, including the House of Commons

The Pneumatic Age to the Space Age

By the later half of the twentieth century, the popular image of pneumatic tubes had changed from being a technological marvel, to being a symbol of bureaucracy, as they were primarily used by governments and large businesses. George Orwell’s Nineteen Eighty-Four character Winston (like his namesake in the Cabinet War Rooms) used pneumatic tube communications, in the novel to rewrite history based on newspapers delivered by tube.

Despite this, the London street tube system remained in use till 1962, when it was shut down, having been superseded by telephone networks, telexes, and teleprinters. Some of the pneumatic tubes were later used to house telecommunications cables, but most were abandoned and forgotten. Many of the house and ticket tubes likely continued in use for longer, but few records were made of their fate. They were usually just blocked up.

In the end, the Post Office pneumatic tubes had worked reliably, effectively and economically for a century but telephones and modern communication methods have all but rendered them obsolete. Today, the chances of finding a pneumatic tube system in operation are small, although search around and you will find them – mainly for niche applications of speed and/or security for items that cannot be sent electronically.

Pneumatic tubes are still being built into new hospitals for example. They are used to rush samples, medications, x-rays, and reports between labs, operating rooms and nursing stations far faster than a person could do on foot (which can be life critical) and less laboriously. Some banks also still use them to transport documents and money, whilst large stores do so to send receipts and cash securely to safes. Even some large libraries still use them to send request slips. Finally, small tubes send very short half life radioactive isotopes very quickly in nuclear reactors, and even NASA’s original Mission Control Centre in Florida had pneumatic tubes to connect controller consoles with engineering support rooms.

The London pneumatic tube network may be gone and forgotten, but little outposts of the technology still remain.

This is the first in the series on pneumatic transportation technologies. This article was first published on LR sister site LapsedHistorian.com, which has, ironically, since lapsed. It has been slightly edited.

Follow the story of the scaling up of pneumatic technology to a working railway, in LR’s previously published second instalment:

• London’s Lost Pneumatic Railway: The World’s second Oldest Underground

I would like to thank David Holt and Graham F for their excellent contributions and assistance in the writing of this article.