black and white photograph of the Spilhaus clock


Spilhaus Space Clock

According to Dr. Spilhaus:

It is most important to understand that all of the time and position measurements of the sun, moon and stars are subject to many and complicated effects, due to the interaction of every astronomical body on every other body. In order to present this eternally moving rhythm of the universe in a relatively simple manner, it is necessary to simplify the presentation and to deal only with the average or mean time and position of each of the heavenly bodies in which we are interested.

The clock has three dials.  The lower left dial is a standard 12 hour clock, showing time in hours, minutes and seconds.  The small dial on the right contains a map of the world and the 24 hour marks around the edge.  The outside of the dial rotates, showing the time anyplace in the world.

The large dial actually consists of five clear discs that rotate independently.  Each disc displays some information:

THe Five Dials of the Space Clock

Tide Disc. It carries the reference marks for telling the current time of high or low tide and the stage of the tide.
Horizon and Hour Disc carries the 300 and 400 latitude horizon lines and the four points of compass.  A 24-hour solar time scale, in gold numerals, is arranged around the outside. This disc does not rotate.
Moon Disc displays the position of the moon.
Sun Disc displays the sun's position and references the hours for telling sunrise and sunset at both 300 and 400 latitude. This disc also displays the phases of the moon.
Star and Calendar Disc It carries the perpetual calendar on its circumference and in its center a field of stars and constellations. The light blue pointer is used for reading sidereal or star time, and the gold circle line serves as a reference for reading sunrise and sunset.

Dr. Athelstan Spilhaus

"Dr. Athelstan Spilhaus, Dean, Institute of Technology, University of Minnesota, is well known to scientists the world over. He is listed in "American Men of Science" as a meteorologist, an oceanographer, and as the inventor of the bathythermograph, an invention which contributed substantially to our submarine warfare success in WW II."

"Through his meteorological work, Dr. Spilhaus has long had a keen interest in astronomical clock, their history and function. Years ago he conceived the idea of a compact space clock utilizing modern materials not available to early clock makers. Over a period of six years he developed the simple, unique gearing for the various discs of the space dial. He built several models, and finally produced a design for a clock that is considered by many to be a breakthrough in the art and science of clock making.

When Dr. Spilhaus gave Edmund Scientific Co. the opportunity to manufacture and market the clock, they eagerly accepted the privilege. Edmund Scientific Co. has for over 21 years been a well known source of supply for scientists, teachers, hobbyists, and amateur astronomers. In the manufacturing of this unique instrument, everything consistent with good engineering practice has been done."


from "Lots of Time", published by Edmund Scientific Co., Barrington, New Jersey in 1964.

night light dial of Spilhaus clock

The dials look impressive when lit.  The telephone bulbs are wired in series and show a soft yellow light..  The horizon line is the squished circle consisting of a white line.  The small half circle inside the horizon line shows the phases and location of the moon.  The large diffraction grating at the seven o'clock position is the position of the sun.  The visible constellations are shown inside the horizon line. Month and date appear around the outside.

knob colors

The back of the clock shows the various knobs used to set the time and position of the dials in the front. Each knob is color coded depending on which function they will control.  Setting the correct positions of all the discs is complicated but the manual carefully illustrates the correct procedure.

Spilhaus clock front dials

When the works are removed from the case, the various gears become visible. The 12 hour dial turns the rest of the gear train. The 24 hour dial shows the outside hour markings that surround the world map.

number plate from Spilhaus clock
signed clock

Chuck Kichline found the signature in the back of the clock.

My Clock

I first saw my Spilhaus clock while visiting my future grand-parents-in-law. Their clock was beautiful and I was entranced. I admired it and told my girlfriend how wonderful it was. Later, when my girlfriend became my wife, she presented the clock to me as a wedding present.

I found it suffered from broken gears. The gears are Nylon and are pressed over metal bushings. The Nylon, made long ago, shrinks, becomes brittle, and splits. The clock will no longer work.

I sent the clock to Edmunds Scientific for repair. They repaired the clock with the gears they have in stock and sent the clock back. Since the gears were made at the same time as the original gears in the clock, they soon split as well. Contacting Edmunds several years later, I found they were no longer willing to repair the clocks. They did send me several replacement parts and gears, and I was able to get my clock running again.  Unfortunately these gears also soon split due to age.  I then started a quest for replacement gears made from new, more stable materials.


A pdf of the original manual, "Lots of Time", is in a small format.

The clock comes with a detailed instruction book called "Lots of Time." My daughter converted the manual to html format for publishing on the internet. She did an exceptional job, scanning in the pictures, writing html code without the aid of a graphical editor, and checking her results. Please refer to it when you want to learn more about your clock. The manual includes instructions on how to set the various dials and discs.  This manual does not require a pdf reader to view.


The original patent for the clock was issued to Dr. Athelstan Spilhaus on May 3, 1966.  It was number 3,248,866.

The patent provides information on how the various discs rotate and how the clock is constructed.  It shows each one of the dials and the various markings.

Spilhaus Clock Construction Explained

"The Best Of J.E. Coleman: Clockmaker" is a book that answers many questions about clocks. It contained a wonderful description of the Spilhaus Space Clock from a gear train and construction perspective.


Many people purchase the clock and assume it is in working condition.  Unfortunately the 12 hour clock will work but it will be difficult to determine if the rest of the dials are turning at the correct rate.   Every single clock I have examined, in original condition, has split gears.  The clock will appear to be running correctly, even with split gears.  However various dials will be slowly be losing time, causing the information to be in error.  You will have to set the clock correctly and then look at the clock again in a month to see how much it is off.  Checking the clock every couple of days will not show enough of a deviation to be noticeable.

Shipping the clock.

Removing the works from the case.

Examining, sourcing, and replacing the cracked gears.

Replacing the telephone lamps.

Replacing the Synchron motor and clock train.


Some photos and restoration text courtesy of amateur restorer and patent attorney Ben Langlotz, shown where credited.  Ben also wrote an article about replacing the original lighting with LED strip lights.

Many people remember the old Edmunds Scientific catalogs. I enjoyed reading them as a kid, thinking of all the wonderful experiments I could perform with the items listed. Bruce remembers the clock and sends a note to his brother.