THE DOOR-CLOCK OF THE COMTE D'ONS-EN-BRAY: 1732

"M. d’Ons-en-Bray had created a clock that one winds up without knowing it, by opening the door of the room in which this clock is established."

COX'S BAROMETRIC CLOCK: 1760s

Left: Cox's barometric clock: 1760s In the 1760s the well-known clockmaker James Cox developed a clock which was were wound up by changes in barometric pressure. The work was done in collaboration John Joseph Merlin, with whom Cox also worked on developing automata. Two large glass vessels containing no less than 68 kilograms (150 pounds) of mercury worked as a massive barometer; they were connected together by an ingenious system of cords and pulleys so that the pulleys would rotate back and forth as the atmospheric pressure and so the glass vessels, rose and fell. A rack-and-pinion mechanism converted this to unidirectional motion so that winding of the mainspring occurred on both rising and falling pressures, and there was a safety-device to prevent overwinding. Cox claimed that his design was a true perpetual motion machine, which of course it was not. The clock is shown here without mercury in the vessels. This is probably a safety-measure rather than an economy measure; if my calculations are correct filling the clock to get it working again would cost something like £600. Cox was a well-known clockmaker. He showed his self-winding clock in a private museum along with other fine clocks. When he died in 1788, a Mr Thomas Weeks bought the clock for his museum. It stayed in his museum until his death in 1833. It was not included in the sale catalogue of his effects in 1834, and remained lost until 1898 when it was exhibited at the Clerkenwell Institute. After a period on loan to the Laing Gallery in Newcastle, it was auctioned, and finally acquired by the V & A Museum in 1961. Cox's clock has a Wikipedia page, but it does not give much information.

Left: Cox's barometric clock: 1760s A contemporary engraving of Cox's clock, where it is described as 'A Prize in the Museum Lottery'. Presumably this refers to Cox's private museum rather than that run by Mr Thomas Weeks, as the engraving is dated to 1774. It is not normal for museums to raffle off their exhibits; possibly Cox had despaired of selling it for an adequate sum. Note the confident claim of perpetual motion. In this view, the driving weights either side of the glass vessels can be seen. From the engraving, it appears the clock originally had an ornamental urn perched on top, which now seems to be missing; I assert it looks better without it. Cox's clock is still in the Victoria & Albert Museum in London, but I do not know if it is on display; one of these days I mean to go and find out. You can see more of Cox's work on the V & A Museum website. A biographical review of James Cox has been written by Clare Le Corbeiller.

Left: Advert for Cox's barometric clock when it was in Cox's museum: 1760s After seeing it in Cox's museum, the Scottish astronomer James Ferguson described it as "the most ingenious piece of mechanism I ever saw in my life" (see last line of the text) and contributed to this bit of publicity. Ferguson was no jobbing hack. He became a Fellow of the Royal Society in November 1763. You may need to zoom a bit to make it easily readable.

BERNARDI'S ETHER-POWERED CLOCK: 1875

Left: The ether-powered clock of M. Henri Bernardi: 1875 This clock is powered on the same principle as the drinking bird. The arrangement of bulbs and pipes contains ether, and since the word is not qualified it is presumably diethyl-ether, which boils in the bulbs immersed in water. The bulbs are covered with a fabric net, and are cooled by evaporation when exposed to the air. This condenses the ether in the bulbs, unbalancing the wheel and causing it to rotate. The obvious snag here is that diethyl-ether (CH3CH2–O–CH2CH3) does not boil at normal room temperatures; it boils at 34 degC at standard atmospheric pressure. Dimethyl-ether (CH3–O–CH3) boils at -23 degC so apparently that won't work either. However, the drinking bird normally uses methylene chloride which boils at 40degC. The answer to this conundrum seems to be that the pressure in the bulbs is below atmospheric, so the boiling point is reduced; it can be adjusted to be very near normal ambient temperature by controlling the amount of pressure reduction. Methylene chloride is safer than diethyl-ether because it is neither flammable nor explosive in air; however it is a neurotoxin and very probably carcinogenic, so I'd stay away from it. The La Nature article claimed that a clock on this principle had been running for two months in the laboratory of M. Bernardi, without renewal of the water. The machine has about it a distinct air of Perpetual motion but it is of course no such thing. It is driven by the temperature difference between the bulbs in the water trough and the evaporation-cooled bulbs in the air, working as a Carnot Engine. The temperature difference is very small so the efficency is very low, though I'm not sure how the efficiency would be defined. I don't feel that gets to the ultimate source of the power, and I would be glad to hear any opinions on the subject. There is a similar unsatisfactory situation with the Crooke's Radiometer. I have one of these and it undoubtedly works, but how it works has been much debated. Bernardi has a Wikipedia page, but it does not mention his ether motor. From article in La Nature 1875, p80

This is translated from the La Nature article: "A NEW ENGINE According to the laws of the mechanical theory of heat, mechanical work can be produced by the use of any difference of heat. The solution of the problem of the production of work, obtained according to this principle, was sought in the following way by an Italian physicist, M. Henri Bernardi:" "Two similar glass flasks are connected by a thin tube, also made of glass. The ends of this tube pass through the flasks with a rectangular bend. One of these flasks contains a small tube which makes it possible to introduce ether into the apparatus. The ether is brought to boiling, and when all the air has been expelled, the tube is closed using a torch. * The quantity of ether contained in the system must be such that it fills three quarters of a flask. In the middle of the connecting tube there is a part through which passes a metal axis, on which the whole system can turn. When the ether is equally shared between the two flasks, the device is in an unstable equilibrium. The axle supports sit on top of a rectangular box, which has a slot through which the rotary system passes." "The crate is full of water, into which the flasks plunge alternately in this rotational movement. Each flask is covered with a very fine trellis. It is easy to understand that this device adopts a circular motion." "Due to the unstable equilibrium of the system, one of the flasks, which we will call A, descends carrying all of the ether, while the rest of the space is filled with vapour. The flask A is thus in the water, and the other flask, which we will call B, in the air. The thin layer of water spread over B begins to evaporate, which cools the container and consequently condenses the vapour. The ether thus condenses in B, until finally B contains more ether than A, and plunges in its turn, A rising again. And so on. This circular movement only stops when there is no more water in the box to moisten the surface of the lowered flask." "It would be difficult to mechanically take advantage of this thermo-engine. Also, Mr. Bernardi has modified his device in the following way: the two flasks or balloons described above are connected by a tube whose ends are bent (at right angles) in opposite directions. Three similar systems form a kind of wheel, and the centers of the six balloons are with the tube in the same plane. This wheel is supported on an axle, which presses against the lid of a rectangular box, in such a way that, in its rotation, it always has one half submerged and another emerged." "The balloons are covered with a trellis and the crate contains just enough water for a single balloon to be completely immersed in it. Starting the engine by one turn of the wheel, a continuous rotation is obtained, and through a suitable set of pulleys the wheel can lift a weight or do other work." "A similar thermo-motive wheel has been running a clock in M. Bernardi's laboratory for two months. The balloons are 0.78 inches in diameter, the center to center distance is 3.1 inches, and the amount of ether in each system fills three quarters of a balloon. The clock that this wheel keeps moving is shown above. The water level, by a special arrangement, is maintained at the same height. Mr. Bernardi was able to operate his wheel for three months, without renewing the water or cleaning the balloons. He calculated the quantity of heat displaced by this device and taken from the surrounding environment: it is equivalent, in 24 hours, to 60 wheel movements or revolutions, which are worth half the work consumed in the same time by the clock. **"

* "The ether is brought to boiling, and when all the air has been expelled, the tube is closed using a torch."

I would have though that would be very hard to do without blowing up both the apparatus and yourself. It also gives no hint as to how a carefully controlled pressure below atmospheric could be established in the tubes.

** "He calculated the quantity of heat displaced by this device and taken from the surrounding environment: it is equivalent, in 24 hours, to 60 wheel movements or revolutions, which are worth half the work consumed in the same time by the clock."

This statement is puzzling, for it seems to say the thermal engine only generates half of the power required to run the clock.

Two vital facts are missing from the above account: how much torque does the motor deliver and how fast does it go round? Drinking birds have in my experience a cycle time measured in minutes as water evaporates slowly.

THE AUTODYNAMIC CLOCK OF FRIEDRICH RITTER VON LÖSSL: 1880

Left: The principle of the Lössl Clock: 1880 Both air pressure and temperature variations affect the force on the stacked bellows units at the top of the tank. There was a pressure-release valve to prevent overstressing of the bellows. In actuality the clock used multiple spring-barrels to store energy, rather than a weight. The volume of the tank was 0.5 m3. If it was spherical, it would have been just under a metre in diameter. (98 cm)

Left: The Lössl Clock at Bad Aussee, Austria: 1880 This is the last remaining Lössl clock in the world. It has been standing at Bad Aussee since 1897; before that the clock stood in Vienna but was removed to make room for the building of Vienna's city train network. The conical 0.5 m3 tank was inside the iron pedestal at the bottom. I have read in several places that in later years traffic vibration affected the rewinding mechanism, and so the clock was converted to electrical winding. It seems to me more likely that it was the clockwork that was affected, and the whole mechanism replaced by an electric clock.

Left: Friedrich von Lössl (1817-1907) He has a Wikipedia page in German. Lössl’s workshop was in Vienna (Währing), at AnastasiusUGrünUGasse 35. The first autodynamic clock was erected on 18th September 1880 in the Wiener Cottagegarten (today Türkenschanzpark), and more followed in the City Park (1881) and in the Prater. (1883) In the following years new clocks were manufactured and positioned in Vienna in the Währinger Gürtel (1888) and in the Hernalser Hauptstraße (1891). In 1904 the clock manufacturer Alfon Schauer took over the patent rights for the autodynamic clock system from Lössl. Clocks were erected in the children’s playground in the City Park (1904) and in the Maria-Josefa Park in 1905. (Now Schweizergarten) In 1905 the clock in the Hernalser Hauptstraße was bought by the city of Vienna. Lössl’s clocks (probably not more than fourteen in total) were exported to Linz, Paris, Hamburg and Marburg.

Left: The book of the clock A book was written on the system in 2003; Die autodynamische Uhr des Friedrich Ritter von Lossl, die Uhr mit selbsttatigem Luftdruckaufzug (Friedrich Ritter von Lossl's autodynamic clock, the clock with automatic air pressure winding) Authors: Josef H. Schroer, Deutsche Gesellschaft fur Chronometrie. Print Book, German. Publisher: Gunter 2003 The cover presumably shows part of the clock mechanism, but it is not clear what it does.

Left: The von Lössl patent 69723: 1880 This image is unfortunately not of good quality. At the base is the conical air reservoir A. On top of it are two bellows C, and just above that is the clock mechanism, with its axles F set vertically. The hands were driven by a vertical shaft and right-angle gears. Lössl's clock was unusual in having a conical pendulum. This uses no escapement but allows the clock to move continuously rather than in steps. There is also a Wikipedia page on the conical pendulum. Lössl received the patent from the Imperial Patent Office on 28 October 1880.

Left: The motion-work of the clock The motion-work of a clock is a 1:12 reduction of the minute hand speed to drive the hour hand. The use of four gears is conventional. Source: Wikimedia Commons

Left: The air-motor of the clock You can see the metal bellows (or at least one of them) but unfortunately there is very little information here. Source: Wikimedia Commons

FRENCH ALCOHOL CLOCK BY CHARLES HOUR: 1902

Left: The French Alcohol Clock by Charles Hour: 1902 This thermal pendulum clock was invented by M. Charles Hour; surely no clockmaker was ever more aptly named, and one might suspect the hand of nominative determinism. The clock was wound by the thermal expansion of alcohol, responding to changes in the ambient temperature. The alcohol was contained in the two columns on each side, which were made of copper, presumably to speed thermal transfer. The details are not yet translated, but the expansion of the alcohol was amplified by the two curved levers, which wound up the clock via steel ribbons. Ethanol has a volumetric expansion coefficient of 0.00109 per degC, about five times that than water at 0.000214 per degC. Somewhat better again is ether at 0.00160 per degC, but we're trying to make a clock, not a time-bomb. Ether seems to be the most expansive of the common liquids, unless you count Dichlorodifluoromethane refrigerant (R-12) which has 0.0026 per degC. However the manufacture of the latter is banned as it plays havoc with the ozone layer. The caption says: "Clock that rewinds itself automatically with alcohol" Many thanks to my correspondent Roland for drawing this machine to my attention. Source: La Nature 1902, Trentième année, premier semestre: n°1489 à 1514

FRENCH WATER PRESSURE CLOCK: 1914

Left: The French Water Pressure Clock: 1914 According to Popular Mechanics for April 1914: (p552) "The variations of pressure in the water mains are utilised by a French inventor for the operation of a self-winding clock." And that's all they wrote. Presumably there was a spring-loaded piston, or equivalent, that moved as the water pressure varied with the daily demand cycle; that should provide plenty of power to wind up a clock. Whether it would work with modern water supplies, which one imagines would have good pressure regulation, is another matter. I have not been able to find any data on water pressure variations. Can anyone help? In Paris this invention would have had to face severe competition from the pneumatic clock network, which distributed time over a large area. Google has nothing on this.

CORNU'S THERMAL CLOCK: 1920

Left: Cornu's Thermal Clock: 1920 (1) The heat from the burner vaporises the liquid in bulb B and the pressure drives the liquid into bulb A, causing the arm to tilt. (2) At the same time a cover is moved over the burner so B is no longer heated. It cools, reducing its internal pressure, and counterweight P returns the arm to its initial position. The see-saw action of the arm winds up the clock through a ratchet R. This does not impress; it is hardly convenient or economic to keep a lamp burning continually just to wind up a clock. Furthermore, the heat is completely wasted for half of the cycle. This idea appears to have got nowhere and I can't say I'm surprised.

MEIER'S THERMAL CLOCK: 1926

Left: Meier's Thermal Clock: 1926 This clock was invented by Karl Heinrich Meier of Ruschlikon in Switzerland. It was wound by the expansion of of glycerine in two coiled copper tubes; the coiling was presumably to increase the surface area and so speed the response to ambient temperature changes. The expanding glycerine drove a piston when the temperature rose and wound the clock. Glycerine has a thermal expansion coefficent of 5 x 10-4, while alcohol has 10.8 x 10-4. It is not known why Meier chose glycerine rather than alcohol; perhaps being viscous it was less likely to leak. The durability of the clock obviously depended on the piston and cylinder not leaking. The details of the rewinding mechanism are not currently known, nor is it known if the rewinding occurred for both rises and falls of temperature. There does seem to be an obvious problem here. The entire clock, incuding the glycerine tubes, is inside a glass dome which will much reduce the temperature variations inside it. Source: Living On Air: History of the Atmos Clock by Jean Lebet, pub 1997 by Jaeger-LeCoultre. This gives an incorrect explanation, saying that the distortion of the coils was used for motive power.

Left: Meier's Thermal Clock: 1926 The coiled tubes of glycerine; the piston and cylinder can be seen at the front. Source: Living On Air: History of the Atmos Clock by Jean Lebet, pub 1997 by Jaeger-LeCoultre

Left: Meier's Thermal Clock: 1926 This tells us that Meier was Swiss and gives some more details. Meier was clearly interested in alternative ways of winding clocks. In 1927 he was awarded a German patent for "Automatic winding up by movements of other objects, e.g. by opening a hand-bag, by opening a case, by opening a door; Winding up by wind power by rotating axles, e.g. tachometers." Searches on the career of Meier are not helped by the short career of a Dutch spy also called Karl Heinrich Meier Source: Journal of Chemical Education March 1928

JUNGHAN'S ELECTRONOME: 1927

Left: The Junghans Electronome: 1927 The Junghans Electronome clock was powered electro-pneumatically; the glass bulb in the background contained a heating element which caused the air in the bulb to expand. The increased pressure passed through a rubber hose to moved a piston in the brass cylinder in the foreground, which wound up a conventional clockspring. The bulb was switched on and off once a minute by cam-operated contacts. Junghans acquired the patents for pneumatic clocks, dated 1927, from the inventor, Martin Fischer of Zurich. The clocks were distributed in Germany by Junghans under the name "Elektronome" The four gears on top of the clock are what is usually called the motion work. It is a 12-1 reduction gear train that drives the hour hand from the minute hand. It is joined to the going train of the clock by friction coupling from the cannon pinion, so both hands can be turned by hand to set the time. It is usually outside the front plate of the clock, and beneath the dial.

Left: The Junghans Electronome: 1927 The 'kolben' (piston) has a helical spring under it to return it when the air cools. The pressure generated was sufficent to operate up to six slave clocks with their own drive cylinders. The minute contacts could be used to switch another six electrical slave clocks. No dropper resistor or suppression capacitor is shown.

Left: The Junghans Electronome: 1927 This shows the clock in its vertical operating position. The power comes in at top left. At top right is a dropper resistor, which looks to be adjustable for differing mains voltages. On the right is the compressor lamp. The round thing at the bottom is a multi-way adapter for the compressed air; it is not connected here.

Left: The Junghans Electronome: 1927 The air-heating bulb.

Left: The Junghans Electronome: 1927 This shows a striking version of the clock with four different hammers and chime rods. The 'luftepumpe' (it is not a pump) is the cylinder with the piston moved by the expanding air. The kondensor (capacitor) was presumably connected across the contacts to prevent radio interference. Note the 'J' for Junghans on the air-heating bulb.

THE PUJA THERMAL CLOCK

Left: The back of a Puja clock made by the German firm of Jauch and Schmid: 1940 The notion here is to power a clock reliably when faced with mains electricity of uncertain voltage and frequency. It is perhaps significant that the patent for the principle (No. 714,893) was granted in Germany in 1940. It would work from either AC or DC mains. In Britain AC and DC coexisted for some time; I am not sure if that was the case in Germany; but judging by the advert below it was, and the mains could be either 110V or 220V. At the lower left, shielded by a translucent housing, is a carbon rod resistance that heats the coloured alcohol in the glass vessel just above it. This causes some of the alcohol to vapourise, the pressure pushing the liquid up the connecting pipe to the vessel at top right. As the latter gets heavier the wheel bearing the four vessels experiences a torque that rewinds a remontoire* spring driving a conventional gear train and escapement. This clock has a pendulum-controlled escapement, but models with balance wheel escapements also existed. The firm of Jauch and Schmid was registered in 1930 The images in this section were very kindly provided by John Howell.

*A remontoire, from the French 'remonter' (to rewind) is a spring or gravity reserve of power that can be configured to give a near-constant driving torque because it is rewound at frequent intervals from another power source- usually this was a mainspring, whose own torque would slowly decrease as it unwound. The idea was that rewinding a spring or lifting a weight at relatively frequent intervals isolated the escapement from the variable torque of the mainspring.

Left: Advertising material for the Puja clock movement. The clock shown here has a balance-wheel escapement attached instead of a pendulum.

To save you the trouble of grappling with a German-English dictionary, here are the translations of the salient words in the advert above; "wechselström" means "alternating current", "gleichström" means "direct current", "thermo-aufzug mit glaskolben-laufrad" translates as "thermo-lifter with glass bulb impeller", and "gehwerk" as "movement".

Gangreserve 6 stunden = power reserve 6 hours. Unruhwellen = balance shafts, and zugfedern = tension springs. I'm not too clear what the last two words are getting at; it looks like two different models, and perhaps refers to pendulum and balance-wheel versions.

Left: Another Puja clock movement This clock also has a balance-wheel escapement attached over a hole where the pendulum would go. It occurs to me that this arrangement must be very inefficient; it looks as though much of the heat would escape without doing anything useful. Presumably the translucent trough shown in the first picture helped to keep the heat in. I also wonder if the Puja clocks were prone to catching fire. This model is for 220V mains.

Left: Another Puja clock movement This is a different clock, with differently-coloured alcohol and a neater escapement mounting. A modern wire-wound resistor has been fitted into the heater spring clips.

THE ATMOS CLOCK: POWERED BY TEMPERATURE AND AIR PRESSURE CHANGES

Anyone interested in oddly-powered clocks will have heard of the Atmos clock, which appears to be mostly powered by changes in temperature, and not, as its name might suggest, solely by changes in atmospheric pressure. A flexible metal capsule is filled with an inert gas and a little ethyl chloride, which vapourises as the temperature rises, causing the bellows to expand, and vice versa. A chain transfers this movement to wind the mainspring. A torsional pendulums with a long period is used to minimise the power required.

Left: An Atmos clock A temperature variation of only one degree in the range between 15 and 30 degrees Celsius, or a pressure variation of 3 mmHg, is said to be sufficient for two days' operation. I don't know if it is the case, but that seems to imply that the clock would stop working if the temperature fell below 15 degrees and stayed there, with the ethyl chloride remaining liquid. This is of course very possible in Winter. I also wonder how it copes with thermostatically-controlled central heating. The torsional pendulum makes only two oscillations per minute, which is 1/60th the rate of the standard seconds pendulum in a conventional clock. Because of the very slow movement of the gear train, no oil is used; it is claimed no measureable wear occurs.

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OTHER WAYS TO POWER CLOCKS