What do you remember most vividly about your first visit to Paris? For me, more than 20 years ago, it was the astounding range of merchandise in shops and galleries, the parks, and the cleanliness of the city.

For a visitor in 1881, it was the clocks. He marvelled “that the clocks throughout their hotels were, what is unusual with hotel clocks, keeping accurate time.” He was also astounded to find “numerous clocks standing on graceful light iron pillars in the squares, at the corners of streets, and in other conspicuous positions about the city.” Parisians lingered by these public clocks to set their watches. The one shown below stood in front of the Church of la Madeleine.

That visitor was a French-born but London-based civil and electrical engineer called Jules Albert Berly, editor and publisher of J.A. Berly’s Universal Electrical Directory and Advertiser. He had travelled to Paris for the 1881 Exposition Internationale de l’Électricité, the world’s first international electrical exhibition. But to his amazement, these remarkable timekeepers were neither powered nor regulated by electricity.

He presented a paper in London and published an article in the 14 January 1882 issue of American Architect and Building News to spread the word about “The Distribution of Time by a System of Pneumatic Clocks.” Interestingly, he does not talk of telling time but of distributing time, as if it were a commodity such as water or gas.

The Parisian system was a model of elegant design and technology. The air came from compressed air pumps and was sent through wrought iron pipes and then on to lead pipes or rubber tubes to the clocks. Every minute, a 20-second pulse of compressed air entered the clock. The system worked 24 hours a day, seven days a week, without interruption.

The key mechanism in each clock – not something found in conventional spring and weight clocks – was a small bellows. In Berly’s words:

Every minute the pressure of the air raises the bellows, and a rod attached to the upper bellows-head actuates a lever which engages with a wheel provided with 60 teeth, which is rigidly secured to the minute hand arbor or shaft. The wheel rotates the distance of one tooth every minute, and a weighted pawl on the other side of the dial checks the movement.

If one watched closely, the minute hand did not move steadily as is the case with most clocks today. It moved once a minute in a single jump. The hour hand was rotated by means of the usual dial wheels. A chime could be activated by a second bellows.

Pneumatic clocks came in a range of designs to fit into any decor. Alternatively, conventional clocks could be retrofitted with the bellows mechanism. Since buildings were not designed for compressed air distribution, these retrofits required pipes or tubes running along interior walls to connect the clocks to the central system. An 1880 article in Scientific American suggested that the lines leading to the clocks could be “colored the same as the wall paper or woodwork of the room, so as not to be easily perceptible.”

Coal-fired steam engines powered the air compressors from a central plant. Because the Seine floods periodically, the equipment was placed higher than the expected flood levels.

Compressed air from the plant left at a pressure of 15 to 45 pounds per square inch (about 1 to 3 atmospheres) for storage in a high-pressure air tank. From there it travelled through a pressure regulator to a low-pressure storage tank or accumulator. Its release was controlled by a distributing clock, shown below. The driving weights were lifted by compressed air to keep the clock running and on time.

 

An automatic timing mechanism opened a valve to release a 20-second pulse of air every minute and then the valve closed for 40 seconds. The 20-second-on, 40-second-off cycle was repeated every minute. The pulse of air travelled to every receiving clock, be it in a private home or office or in a street or public building, and advanced the minute hand by one minute. The air travelled through a system of pipes, many of which ran through the Paris sewer system. There were two distributing clocks, so that if one malfunctioned, an electric alarm sounded and a workman could pull a lever and bring the other clock online to control the flow of air.

As described in the July 10, 1880, issue of Scientific American, from which the illustration above is taken, the main air lines were made of wrought iron about 1-1/16-inch diameter. To direct air to a clock, the main line was tapped and a stopcock and 3/5-inch lead pipe was attached. Inside the dwelling or building, lead or rubber tubes 1/8 inch in diameter were attached to the lead pipe. These went to individual clocks.

Pneumatic clocks quickly became popular. The spread of a new technology is often helped immensely by key adopters. And in a city known for luxury, Le Meurice Hotel stood at the pinnacle of luxury accommodation.

In the 18th century, French postmaster Charles-Augustin Meurice realized that the growing number of English tourists visiting the continent wanted the comforts and conveniences they expected at home. He opened the Hotel Meurice in Calais in 1771 followed in 1815 by the Hotel Meurice in Paris. Located since 1835 on the Rue de Rivoli near the Tuileries Palace, it stood out for quality, convenience, and refinement.

In 1880, the Hotel Meurice installed 148 pneumatic clocks, a service for which it paid 56 pounds sterling a year, the same amount it paid each year for its water supply. Accurate clocks were a status symbol and the Hotel Meurice was an early adopter. The Hotel Meurice had electric lights by 1891 and telephones followed a few years later.

Although Paris showcased the technology, it was not a French invention. In the 1870s, compressed air was an emerging technology used in mines, tunnelling, and factory equipment. J.A. Berly traced French attempts to make compressed air clocks back to 1864 and other sources mention various attempts in the 1870s.

However, the breakthrough came in Vienna, with the inauguration on 23 February 1877 of the first public service for the distribution of time by compressed air. Carl Albert Mayrhofer of Vienna invented the system and in addition to French, U.K. and Belgian patents took out U.S. patent 215,381 in 1877, “to keep a number of clocks in regular and isochronous motion by pneumatic power.”

Mayrhofer’s American patent was assigned to Victor Popp and Ernest Resch (misspelled Resgh on the patent), also of Vienna. Inventors are not always the best people to bring ideas to commercial fruition and Popp and Resch appear to have created the working system and undertaken its commercialization. In the 1878 Paris Exhibition their system received a silver medal.

Their proof-of-concept work was done in Vienna. A small number of publicly accessible clocks worked for a year and the technology was improved so the minute hand moved every minute rather than every two minutes. However, when in 1880 they petitioned the Viennese municipal authorities, they were refused the 50-year monopoly they sought. The Viennese Pneumatic Clock Company ended its operations.

Meanwhile, on 1 August 1877 the Compagnie Générale des Horloges Pneumatiques had been formed to deploy the Système Popp-Resch in Paris. In November 1878 the company received permission to lay up to 10 km of pipes in the sewers of the first and second arrondissements, connected to a central compressed air plant at 7, rue Ste-Anne (there was also a showroom at that location, shown below).

The following month the company obtained permission to deliver pneumatic time to private dwellings. The big moment came on 15 March 1880, with the inauguration of the public service, including four clocks (some with multiple dials) on lampposts on the grand boulevards.

By the end of 1881, the sewers were carrying nearly 32 km of pipes and 750 houses with a total of 4,000 clocks depended on the pneumatic system. And this was only in the first and second arrondissements.

On 9 July 1881 Paris awarded La Compagnie générale des Horloges pneumatiques a contract with a 50-year monopoly from 1 July 1881 to 30 June 1931. Under the terms of the agreement, the company would extend coverage arrondissement by arrondissement, until by the end of 1886 the entire city of Paris would have pneumatic clock service.

Much was made of the fact that the city was to be fitted with clocks as a public service; this included clocks at cab stations and kiosks, street clocks mounted on lampposts, the clocks of the Hotel de Ville and all the arrondissement mairies, and clocks in police courts and police stations, municipal barracks, theatres, schools, markets, parks and squares, churches, and even slaughterhouses.

The city of Paris paid for these services. The cost depended on the size of the clock. The payment schedule was on a sliding scale decreasing every five years for the first 25 years of the contract and for the remaining 25 years of the 50-year contract there was to be no charge. At the same time, the agreement specified annual payment from the company to the city for installing its pipes in the sewers.

The civic officials of Paris made an excellent choice when they opted for the compressed air system. Although electric clocks were feasible at the time and potentially more accurate, they would have been much more expensive. J.A. Berly regarded the electrically regulated clock as “more a delicate scientific instrument than a practical apparatus for the rough-and-ready purposes of ordinary life… pneumatic clocks are not regulated to fractions of a second, but, after all, nobody ever wants to keep appointments by fractions of a second, and trains have not arrived at that pitch of punctuality that it is necessary to calculate by seconds whether one can catch a train.”

The clocks served Paris exceptionally well until the great flood of 1910, when the Seine rose high enough to flood the compressed air plant and on 21 January 1910 at 10:53 a.m., the thousands of clocks on the system stopped. However, the system was repaired and pneumatic clocks remained a feature of the city until 1927, when the service was discontinued.

Text by Norman Ball; illustrations from Paris en images, Wikipedia, and Scientific American.