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Book on Norwegian Astronomical Clock

Bill Ward

NAWCC Member
Jan 8, 2003
Here is my review which appeared in the October Bulletin:

The Clockmaker Rasmus Sornes
Tor Sornes

Edited and published by The Borgarsyssel Museum, Sarpsborg, Norway, 2008
HB 7 in. (18 cm) X 9 5/8 in. (25.4 cm)
144 acid-free calendared pp., incl. Table of Contents, Forward, Introduction, Prologue, 129 pp. text, diagrams, technical drawings, many color and BW photos, and genealogical table, and 4 pp. appendix of mostly astronomical terms.
Available from the Borgarsyssel Museum or the NAWCC Gift Shop for $29.95

Rasmus Sornes (1893-1967), Norwegian clockmaker, perhaps needs some introduction He was a mostly self taught inventor and clockmaker, best known for his construction of four astronomical table clocks, built to rival the most complex clocks in the world. The last, and most evolved of these, was in the Rockford, Ill, Time Museum collection. It ranks as one of the most advanced clocks ever made.

This book, by Rasmus’ son, Tor Sornes, may be divided into two sections. The first consists of family recollections of the life of the clockmaker, and is by far the more entertaining. Although the author is not a native English speaker, and probably exhibits a certain Scandinavian reserve, his warmth, humanity, and love for his subject shine through. And what a subject it is! Rasmus Sornes belongs to that class of men, like John Harrison and David Rittenhouse, whose native genius could never be extinguished, despite ill-starred adversities and impediments.

Born into a poor but ancient farm family in rural Norway, he had limited educational opportunities (school only every other day). Although he attained good grades, he treated attendance casually, preferring to work on his machines and inventions. These were the wonder of the neighborhood; they included a self regulating pump to water the livestock, a tractor made from an old car, a steam engine for a small boat, a milk separator, hydroelectric power for a nearby farmer, and an automatic incubator - which turned the eggs! All of this was made with self-built equipment.

After finishing grade school, he tried to find a spot as a watchmaker’s apprentice but was rebuffed everywhere. This he attributed to a prejudice against farm boys as being clumsy and stupid. Perhaps this resentment, which rankled him for life, was the impetus for his horological achievements. Later in life, he had the satisfaction of hosting yearly visits from the graduating classes of the Oslo watchmaking school, to allow the students to wonder at his mechanical expertise.

But perhaps those old watchmakers were right, in a way - a simple apprenticeship was not for Rasmus. He spent several restless years trying out vocations: a bicycle factory hand; a mechanics workshop helper; a stint at the Stavanger Electric Works; he ran a farm equipment workshop: but he still invented, e.g., a hay transport device. With a certificate from the Stavanger Technical Institute, he became an electrical fitter, then an engineer for the Jorpeland Power Station. All this by age 21!

He became interested in photography, astronomy, and radio. This last led to a job in 1921 with a ship-to-shore radio relay station. In 1922 he started a radio broadcast station, perhaps Norway’s first, in his home. This only operated for about a year, before the local electric company had it closed. - they feared it was leaching off all their power into the air!

In 1931, he moved his young family to the island of Jeloy, where his employer was building a new radio station. Rasmus built himself a new house, bristling with antenna wires and strange devices, such as a rotating irrigation cannon on the roof, for the surrounding gardens. This was liable to soak unwary visitors, or forgetful occupants! Another of those devices was a large telescope (the second largest in Norway). During the April 1940 surprise invasion of neutral Norway by the Nazis, the neighbors asked Rasmus to remove it, as they feared it would be thought a gun and bring bombs down upon the area.

Under the Nazi occupation, Rasmus was apparently involved with the Resistance. Evidence of this is a secret radio he built, disguised as a functioning voltmeter, now in the Oslo technical museum. Possession of this during the occupation was a capital offence.

This section of the book contains many entertaining anecdotes, which also throw light on aspects of those desperate times, and how people coped with them. For example, Tor explains that in that time, most shoes were made of fish skin, which couldn’t have worn very well. Rasmus made shoes for his children of discarded auto tires, which embarrassed them - after all, wasn’t it strange enough to be the offspring of the village wizard?

But my favorite story is about how Rasmus put a lens in the door of the outhouse, thus converting it into a camera obscura. A perfect, albeit inverted, moving image of the main house, and everything around it, was projected on the inside wall.

The second section of the book is about the four clocks which Rasmus began in 1935. Tor does not reveal, nor speculate upon, the origins of his father’s great obsession. One might wonder if he had any contact with Jens Olsen, the Danish maker of another great Scandinavian astronomical clock. Olsen was a generation ahead of Rasmus, having been born in 1872, and must have completed his apprenticeship when Rasmus was born in 1893. Although Olsen’s plans were complete by 1922, his clock’s construction was not commenced until 1944, nor finished until 1955. So it is not likely that Olsen was a source either of inspiration or information for Rasmus. Tor dismisses Olsen’s clock as almost “a factory made product,” because it was built in a workshop at the Danish Technological Institute. He does admit Rasmus’ debt to Schwilgue’s Strasbourg clock, but perhaps does not realize that this clock also was made by a large team of workmen. In fact, even in his own time, Rasmus Sornes was an anomaly, a throwback to the time when men like himself were able to complete such works wholly on their own.

Possibly Tor is also not aware that Schwilgue’s masterpiece was also Rasmus’ technical model. The complex mechanism which computes the subtle deviationss of the moon’s orbit from the simple ideal (the anomaly, the variation, and the evection), was insofar as I have been able to determine, invented by Schwilgue. This device consists of concentric vertical cylindrical cams, one above the other, and riding on each other, such that the effects are additive. This was used as input to Schwilgue’s computus, the mechanical computer which calculates the date of Easter. Schwilgue’s solution to this problem was the first successful attempt in centuries. How Rasmus learned of this is a mystery. Olsen made a pilgrimage to Strasbourg around 1900, but was annoyed to find that the great clock was only shown for one hour a day, and that the important mechanisms were concealed under a green cloth. To see the mechanism, he finally resorted to hiding under the cloth! So far as we are told, Rasmus never journeyed to Strasbourg, and it’s not likely that he learned the secrets of Olsen’s masterpiece before it was even built.

However that may have come to be, Tor does not hold back in revealing the innermost workings of his father’s chef d’oeuvre. The book is larded with reproductions of the original drawings, labeled in Norwegian, but with English translations and captions. A creditable, if non-mathematical, job is done of explaining the complexities of astronomical clock design - perhaps the best job in English. Most of the drawings include tooth counts, the result, no doubt, of long hours of hand computation in the days before electronic computers or even calculators.

Rasmus experimented for fifteen years with his own electromagnetic chronometer escapement, but he eventually (after clocks 1 and 2) reverted to a seconds weight- driven Invar pendulum with an electric remontoire, which provides correction to the normal synchronous motor drive. Thus, though electrically powered, the clocks are under total mechanical control. The chronometer escapement is not described - perhaps Tor will grant us a paper on that subject someday.

This book is important because it documents some of the world’s greatest clocks, and the independent genius who made them. It belongs in the library of every serious horological book collector. It should be read by all who have an interest in advanced horology, or in the social history of early 20th century Scandinavia. Highly recommended!

Bill Ward
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Fortunat Mueller-Maerki

NAWCC Star Fellow
NAWCC Fellow
NAWCC Life Member
Sep 23, 2001
Bill is correct. The new book on the Sornes clocks is an interesting book, as it sheds much light on the maker of one of the great complicated clocks made in the mid 20th century.

On reading the book however I wished the reviewer had also pointed out the shortcomings of the book. It is clear that the author of the book (the son of the great clockmaker) has a rather limited knowlege of horological history, and the the history of complex astronomical timepieces in particular.

He does not claim to be an expert on these mattes. His memories on the life of his father are compelling reading for anybody who seeks to understand the motivation and personality of a genius lone-wolf clockmaker. But when the author veers into detours on the history of clockmaking in general there are several outright mistakes and even more misleading half-truths. The book was obviously not written for a horological audience.

I am certainly glad that an English translation was published, not to many horologists can read the original Norwegian text, but the person who helped the author with the translation obviously is not familiar with the English language horological terminology. Not all of that is due to translation only, the author tried to write for a general audience, but when he talks about technical astronomical and horological concepts, there are precise words for certain concepts and using a non-technical, vague term does little to help the lay reader and hinders the understanding of a specialist reader.

Clearly both the clockmaker and the author were inspired by the Strassbourg cathedral clock, but it seems that probably neither of them has actually seen it (That the book describes the clock being in the cathedral tower , while in actuality it is the northern crossing on the ground floor level, is an annoying error, but symptomatic for the cavalier way several facts that deal with horological history are presented.

The book would be much more valuable had there been a lector/editor involved who knows horology and knows English.

Fortunat Mueller-MAerki
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Bill Ward

NAWCC Member
Jan 8, 2003
Yes, certainly this book is for the layman. But, in fact, so far as astronomical horology goes, most readers (even including readers of this message board) are amateurs. It’s hard to think of anyone in this field who ISN’T an amateur. And it’s equally hard to find explanations that bridge the gap between the childishly simplistic (e.g. that the moon orbits the earth in a circular path which lies in the plane of the ecliptic, which is often taught in college) and the real-life complications (e.g. the lunar 3-body problem which made Newton tear his hair for decades, but which he never solved). Personally, I think Tor did a very creditable job, without turning his memoir into a textbook; the book is, after all, about his father, the clockmaker, as the title says.
However, for those with an appetite for pages of partial differential equations, I can highly recommend the real deal:
Fundamentals of Celestial Mechanics, JMA Danby, 1962, but revised 2nd ed. available; CD with BASIC or Turbo-Pascal source and compiled code available separately, both from:
And for those who just have to know exactly how NASA does it, and like to write their own code, there’s:
Astronomical Algorithms, Jean Meeus, 1999 (2nd ed. 2005 printing is most current) and also:
Mathematical Astronomy Morsels (same author); both available from:

But, of course, Tor knows his own limitations, and so (as noted in the Forward) had his manuscript vetted by Prof. Kaare Aksnes and Prof. Rolf Brahde at the University of Oslo’s Insitute for Theoretical Astrophysics, and also Dr. Ellen K. Henriksen and Prof. Helge Karlsen. I am familiar with Prof. Karlsen’s work, at least, as he is the author of at least four articles in German and English on astronomical horology, including the cover article for the March 1983 Antiquarian Horology journal, “A 16th Century Astronomical Table Clock by Jost Burgi with Non-Uniform motions of the Sun and Moon”, and “A New Steffan Brenner Differential” in Antiquarian Horology Sept. 1982, as well as “Die Chor-Uhr in der Kathedral von Chartes” in Klassik Uhren, 1, 1996. As I do not read Norwegian, Danish, or Swedish, I cannot cite any of his articles in those languages.

Still, mistakes do creep in, as always. Perhaps Tor meant to say that the Strasbourg clock is in “a” tower in(side) the cathedral (which is true) rather than “the” tower. In any event, Fortunat is doubly incorrect about its location: it’s not in the “crossing”- the crossing is where the nave and transept intersect (see the “Penguin Dictionary of Architecture” by John Fleming, Hugh Honour, and Nickolaus Pevsner, or my own Professor Cyril Harris’s architecture dictionary, or just Wikipedia); nor is it in the northern part. It’s in the south transept, which is the traditional place for horological implements in churches (at least in the Northern hemisphere) since most of them were, at one time, sundials.

Fortunat Mueller-Maerki

NAWCC Star Fellow
NAWCC Fellow
NAWCC Life Member
Sep 23, 2001
Thank you Bill for correcting my errors. I stand corrected, Bill of course is correct I meant to say the transcept not the crossing (my cathedral architecture terminology is not up to snuff which would upset my wife greatly as she is a cathedral docent). And I have no idea why I wrote North rather than south, that I know. Actually to the right of the clock in the south transcept there is also a fragement of a meridian line on a wall, which underlines Bills point about horology usually being in the southern end of churches.


Lynne Gillette

Registered User
Aug 28, 2008
In a Tudor Cottage named Squirrelton
I guess I should check the message board every morning! This is a book I do not have and it sounds like a very interesting read. I was at the museum today but was doing other things and in a rare occasion did not visit the gift shop.
It would have been a great way to spend some time tomorrow while the wife is out shoveling the snow!

Mr Kirk

Registered User
Sep 23, 2012

About clock No. 4

In 1966, mechanical genius and self-taught clockmaker Rasmus Sørnes from Norway completed his 4th and last astronomical clock after eight years of work. The word clock is a bit misleading, it would be more accurate to describe it as "a mechanical real-time model of the solar system", as it not only shows the current time, but also the current:

  • Sidereal time
  • Moon phase
  • Sunrise and sunset at a certain latitude
  • High and low tide
  • Celestial globe
  • Julian number
  • Sunspot period
  • Gregorian calendar
  • Solar and lunar eclipse prediction
  • Orrery (planetarium)
  • 25 800 year precession of the equinoxes
  • and more
In addition to this, the clock can be run forwards and backwards at high speed to predict solar and lunar eclipses and to show all the other data above at a certain time.

Where is it now?

While the three preceding clocks still are at known locations in Norway, clock No. 4 has disappeared. It was sold by Rasmus Sørnes' family to the Time Museum in Rockford, USA in the 1970s. The museum closed in 1999, and for some years the clock was on display in Chicago's Museum of Science and Industry, but in 2004 it was sold by Sotheby's to an unknown buyer.


In 1957, when Russia placed Sputnik in orbit, Sørnes made a model of the satellite rotating around the globe. It showed in real-time the location of Sputnik relative to the earth, and could be used to predict when and where the satellite would be visible. To Sørnes' disappointment, this device got more attention than the astronomical clocks.
Starting with clock No. 1, Rasmus Sørnes seems to have spent most of his spare time working on what would become in total four astronomical clocks, each one more complicated, accurate and beautiful than the previous one. He retired from the radio station in 1958, and then he started working full-time on what would become his masterpiece, clock No. 4.
In spite of this, he never said no to helping old friends and neighbours, whether it was with clocks or radios. One year after finishing his last clock, he was struck by stroke while standing at the turning lathe, and he passed away a week later, at Moss hospital, February 15th, 1967.

Clock no 4:
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