Sep 042005

Long before the time of laser lightshows in planetariums, armchair star-travellers tried to reproduce celestial mechanics with earthly wheelworks and brass gears. An art form practised today by only two remaining orrery makers.

The road to the stars is a narrow path – thickly overgrown and bumpy, too. It leads to a remote little cottage near Hebden Bridge, in the North of England. You enter through a low door, walk up narrow stairs and step into the workshop of John Gleave. From the gentle hills of the Yorkshire Pennines outside the window he soon takes you on a journey around the sun, passing Mercury and Venus, taking a close look at the Earth and the Moon and spinning, with a twist of his hand, out to Mars, Jupiter and Saturn. Even though the 60-year-old is a veteran star traveller, he is neither a rocket scientist nor an astronomer. A look around reveals what his universe is made of: small gears of varying sizes, brass discs and rings engraved with dials and zodiacs, hand-painted spheres and polished wood. John Gleave is an orrery maker – one of only two worldwide still practising this almost extinct profession full-time.

Close up view of an Orrery's mechanics.

Close up view of an Orrery's mechanics.

“Orreries are mechanical models of the solar system”, explains Gleave, “designed to illustrate the motion of the planets and the moons around the sun.” Operated by a crank, clockwork or a motor, they can be as simple as a little Earth and Moon circling the Sun or as complex as a so-called “Grand Orrery” reproducing also the movements of the outer planets and their major moons. The term ‘orrery’ was coined in 1712, when Charles Boyle, the fourth Earl of Orrery in Ireland, ordered an Earth-Moon-Sun model from John Rowley, a London based scientific instrument maker.

The Earl, the Earth and the Moon

While an exact date can be put to the naming of orreries, their beginning is blurred. Rowley’s orrery definitely wasn’t the fist of its kind. Cicero described two ‘spherae’ made by Archimedes around 200 BC showing the relative motion of the sun, the moon and the earth. Unfortunately, no other evidence of such a ‘sphera’ survives. Instead, the two thousand-year-old Antikythera Mechanism (see engine 2/2005) surfaced, a highly complicated wheelwork, said to be an ancient orrery. “But I think it was more like a calender”, opposes Gleave, who is a kind of expert in this field having rebuilt several of these mechanisms. Other geared astronomical instruments predating Boyle’s orrery were astronomical clocks, already highly sophisticated in the 15th and 16th century as the famous examples in Prague or Strasbourg prove. In 1677, the Dane Ole Rømer, a contemporary of Cassini (see engine 4/2004), built a so-called Joviable, a model of Jupiter and its four largest moons, to illustrate his observations. But the credit of having invented the orrery goes to George Graham, who built a mechanical model of the Earth’s and the Moon’s complicated path around the sun between 1704 and 1709. The model John Rowley made for the Earl of Orrery seems to be an improved version of Graham’s mechanism.

Orrery maker John Gleave with one of his creations.

Orrery maker John Gleave with one of his creations.

“In the beginning orreries were only made for scientific or educational institutions or rich collectors, growing constantly in size and complexity. In Victorian times they became quite popular when cheaper models were made available. But finally, with the introduction of optical planetariums, orreries almost disappeared”, is how Gleave summarizes 300 years of orrery making. The demise probably started in 1770 with Adam Walker’s Eidouranion, a transparent orrery with a projector, and their fate was finally sealed in 1924 when Carl Zeiss revolutionised the visualisation of astronomic principles by introducing his projector, the standard in planetariums until today.

The Majesty of Celestial Mechanics

Why compete with nothing more than brass gears and wooden boxes against these fancy light shows? Why does someone want to learn an almost extinguished art? “About twenty years ago a novel got me interested in the movement of the planets”, Gleave recalls the beginning of his passion, “and I thought an orrery would be a good way to visualize the Copernican principles. I soon had to learn that these things are collector’s items and very expensive to own. But, working as an artist and painter at the time, the mechanical beauty and craftsmanship of these mechanisms appealed to me and since I always wanted to work with metal, I decided to build my own. My first orrery was a simple pulley-and-cord model. Later I took a clockmaking course and improved it with gears. For an artist like me, working out the gear ratios and transmission wasn’t easy at all, I guess my head wasn’t wired for it.”

It seems he has now mastered the mechanical arts quite well: around 170 orreries have left his workshop so far, from simple Earth-Moon models to elaborate Grand Orreries including a ringed Saturn with its largest moons moving independently. Sometimes he even gets carried away a little. “The largest orrery I ever built was four feet across”, he recalls, “and I found out too late that it didn’t fit through the door. Ultimately, I had to dismantle it and complete it in my neighbour’s garage. Today I prefer my orreries not to be bigger than three feet.”

The model he is currently working on will get through the door fine. Though not a Grand Orrery, it’s nevertheless a proof of his artistry: The elaborate mechanism shows the path of Mercury, Venus and the correct movement of the Moon around the Earth. A large brass bar carries a multitude of gears around a sun the size of a golf ball. “The bar is necessary to counterweight the complex mechanics to reproduce the Metonic cycle of the Moon and the inclination of its orbit”, Gleave explains, which was and still is probably the main reason to build an orrery in the first place.

Meton of Athens discovered in 432 BC that after approximately 19 years the phases of the Moon recur on the same days of the same months. A finding that, for example, is used in the computation of the date of Eastern. Since the Moon moves with the Earth around the sun, the time to complete its cycle differs depending on the reference point – either the Earth or the stars. Complicated? What about the fact that the Moon’s orbit is not, like that of most other moons, in the Earth’s equatorial plane but inclined by about five degrees to the plane of the ecliptic – the reason why lunar eclipses don’t happen every month, be it a synodic or a sidereal. Totally lost? Get yourself an orrery. A few turns on Gleave’s masterpiece and you will easily see what is so difficult to explain.

Although such complications were already present in Rowley’s original orrery, Gleave doesn’t stick too close to the original designs in preference of his own designs. “Generally you could say that none of my orreries are replicas of antecedent models. I guess I’m still an artist working with metal and my main aim is to produce orreries that are exact and aesthetically pleasing.”

Where Art Meets Mechanics

A fine sense for art seems to be as much a prerequisite to become an orrery maker as a good mechanical understanding. “Besides that you need the patience of Job, the wisdom of Salomon, the strength of Samson and a bank account the size of Rockefeller’s”, says Brian Greig from Melbourne, Australia, in an attempt to explain his efforts at making a living from orrery-making. And a quite successful attempt it is, at least for the orrery lovers. In his case, it was the mechanical beauty of an orrery he once saw in a Sotheby’s catalogue belonging to his uncle, an antique collector, that sparked the interest in these mechanical masterpieces. A spark that in 1990 finally became a flame when the former mechanical designer built his first orrery.

Today he offers a great variety of orreries from the classic English type to specialised orreries such as tellurians showing Earth’s seasons, lunariums concentrating on the complicated motion of the moon, Jovians and even a Mars orrery using elliptical gears to reproduce Kepler’s Laws of equal space and time – a complication omitted by most of the classical orreries, which concentrate just on periods but not on astronomically correct orbits. “But my favourite is the replica of Edward Troughton’s orrery from around 1800”, claims Greig referring to the Mercury-to-Moon model of the solar system. “It took me about three years to finish the first one.” That included pestering the museum curator for months to do a little brass rubbing on the original in the Science Museum in London. Greig is absolute passionate about details. He is the kind of person that broods for hours with a magnifying glass over photographs of orreries counting teeth and sometimes even gets thrown out by a curator because he suggests measuring or, even worse, X-raying one of the precious originals.

Cutting the Time Away

Once he gets the layout, Greig locks himself in his workshop milling and filing the time away. Cutting gears is a time-consuming art. With a guillotine he first cuts out squares from a sheet of brass. In a lathe each square is then turned to a disk with the desired diameter. These discs are finally clamped into horizontal milling machine with an index plate and the gear is cut tooth by tooth. Attempts to rationalise this process have failed badly: “We once tried to produce gears with a modern laser cutting machine, but the shiny brass burned the mirror of the machine and shut it down for about a month.” Although their work is similar, most of the traditional orreries were not made by clockmakers but by scientific instrument makers. A trend 63-year-old Brian Greig is eager to continue: “I actually don’t like clock shops, they give me the feeling that my time is ticking away.”

Brian Greig and one of his favourite Orreries. (Image: Greig)

Brian Greig and one of his favourite Orreries. (Image: Greig)

And time he needs. Completing a standard orrery takes months, the annual production averages no more than three or four. Most of these orreries are sold, as they were in past times, to educational institutions, museums or rich collectors to ornament their library. Prices are about 3000 Euros for a standard Earth-Moon orrery. But although a visit to the planetarium is much cheaper and probably more entertaining and a computer program can take you across the solar system in a most realistic way, orreries still hold a universal fascination that automatically attracts everyone who comes near one of these mechanical masterpieces and almost instantly creates the wish to own one. Maybe it’s the warmth radiating from brass, enamel and wood, that makes cold astronomical equations more accessible. Maybe it’s the reassuring fact that the distant planets endlessly follow paths that can be reproduced by man-made wheelworks. Or maybe it’s simply because an orrery is as close as you can get to the dream of travelling to the stars with just a twist of your hand.

Matthias Meier
Brian Greigs Orrery-Seite ist die wohl umfassendste zum Thema im Internet. Viele unterschiedliche Typen, Hintergrundinformation und Pläne eines Märklin/Meccano-Baukasten Orrerys.
Internetseite von Peter Grimwood, ein in diesem Artikel leider nicht genannter, aktiver Orrery-Macher
Das Science Museum in London ist Heimat des namengebenden Orrerys von Rowley und Wrights Grand Orrery von 1733.
Ein „Human Orrery“ des Armagh Observatoriums in Irland, bei dem die Besucher die Rolle der Planeten übernehmen können.
Zwei von vielen Orrery-Programmen. Diese hier können online betrachtet werden.







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