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History of the Botjes Planetarium

Academics / Departments & Programs / Physics & Astronomy / Wildrik Botjes Planetarium / History of the Botjes Planetarium

  • Botje Hinderikus Bos
  • Henry B. (Hinderikus) Bos
  • Henry and Bertha Bos

The Botjes Planetarium has traveled across continents and been passed down the generations.

Wildrik Botjes was a goldsmith and watchmaker working in Nieuwe Pekela, about 20 miles southeast of the city of Groningen in the Netherlands. He was interested in astronomy, and was fascinated with the idea of representing the motions of bodies in the solar system by a mechanical device. As a hobby he constructed the miniature planetarium which is now displayed in North Hall at Calvin University. The construction required fifteen years, and was completed in 1868. Upon completion, he transferred it to his nephew and began work on another planetarium.

Wildrik's nephew, Botje Hinderikus Bos (see photo), was also a watchmaker and an avid amateur astronomer. He brought the planetarium with him when he immigrated to America in 1896. The arrival in Kalamazoo, Michigan, of the wonderful machine was reported in the August 4, 1896 issue of the Kalamazoo Morning News. The planetarium ran continuously throughout his life, with one interruption: the main spring was broken during a storm at sea on the passage to America. Botje repaired the damage himself with his watchmaker skills. Botje in turn handed the planetarium down to his son, George (Tjaart) Bos.

Although George also had an interest in astronomy, he passed the planetarium on to his brother, Henry B. (Hinderikus) Bos (see photo), when he left Kalamazoo. Henry B., a skilled woodworker, kept it in running order, and submitted it to an exhibition in Kalamazoo in 1926, in which it won a first prize ribbon. At some point before this the surface was repainted, with the labels rewritten in English.

When Henry B. passed away in 1968, the planetarium passed to his son, Henry A. Bos. It ceased running soon thereafter. Henry and his wife Bertha (see photo) donated the planetarium to Calvin University in 1989, with the understanding that it would be restored to operating condition and placed on display. It was officially accepted by Calvin University and restored to working order by Prof. Clarence Menninga. It was placed on display on May 18, 1992, and has been kept in operating condition since that time. The donation of the planetarium to Calvin University was reported in a 1992 issue of the Grand Rapids Press.

Newspaper Reports

  • Kalamazoo Morning News, Tuesday, August 4, 1896 (page 8)



    Fifteen Years Required in Its Construction--The Mechanism in Strict Conformity With the Movements of the Heavenly Bodies--Device Owned by a Kalamazoo Gentleman.

    B. H. Bos, who lives at 514 Elizabeth street in this city, is the owner of a most wonderfully devised and ingenious machine from which wonderful results are obtained by purely mechanical means. He calls it a "Planetarium," and by it the complete movement of the planets and everything relative thereto is shown according to the Copernian system.

    Mr. Bos is a Hollander by birth and came to this country last spring. By trade he is a watchmaker. The wonderful machine was built by his uncle, W. B. Bojes [sic], who was a common Holland watchmaker. It required fifteen years for him to complete it, the finishing touches being given it in 1868. It had run continually until last spring, when, while being brought across the ocean by Mr. Bos, who inherited it, it became out of order during a storm at sea. During the summer he has repaired it and now has it in operation again.

    This intricate device which gives an interested observer a comprehensive idea of the movements of the planets and their relations with each other may best be described by taking each dial at a time. It is contained in a box about three and a half feet in diameter and one foot in depth, with glass sides and tops of octagon shape. On its service [sic] are to be seen six dials with numerous pointers, figures and cogwheels.

    Dial No. 1--Shows the days of the week.

    Dial No. 2--Is a common clock dial showing the time of day same as any other clock.

    Dial No. 3--Shows accurately the year round the time of the rising and setting of the sun, which of course varies very much at different seasons of the year. It also shows [c]ommon time and central time.

    Dial No. 4--Is perhaps the most intricate of all, showing the planets, Mercury, Venus, earth, Mars, Jupiter, Saturn, and Uranus, revolving about the sun in their proper relative positions, describing their proper orbits the time which is taken by the planets on the dial to describe their orbits being the same as actually required by the planets themselves in the solar sys[t]em. Thus mercury goes around in eighty-seven days and a fraction, Venus in a little over 224 days, earth in one year, Mars in 687 hours [sic], Jupiter in a little less than twelve years, Saturn in twenty-nine and a half years and Uranus gets around in a little less than eighty-four years. Thus it will be seen how very complicated and slow must be some of the movements. Uranus travels about one inch space on the dial in one year's time, and yet it is continually moving. This same dial shows also the position of any planet in any season of the year and the signs of the zodiac.

    Dial No. 5--Shows the firmament with the stars and constellations, and sun and moon showing when the latter rises and sets.

    Dial No. 6--Shows when the eclipses of the sun and moon will occur. Also shows accurately the various phases of the moon, whether it is full or no moon at all. One hand on this dial shows the "knots" [nodes] and traverses the face of the dial to the right once in eighteen years and 229 days. Another hand goes once to the left in seven years and shows the "points" [of perigee and apogee]. This dial also shows the days of the month. A thread is drawn about the outer edge of the machine by which may be seen the orbits which the planets describe.

    The machine contains ninety five cogwheels and is run by one main spring. It is well worth any one's time to see this truly wonderful piece of mechanism.

  • Grand Rapids Press, Monday, May 18, 1992

    Calvin's gift planetarium is on display

    By Marc Schulhof

    Clarence Menninga speaks very little Dutch. But because science is a universal language, the retired Calvin College professor has been able to restore a small planetarium built in the Netherlands in the mid-19th Century.

    The planetarium was donated to the college by Henry and Bertha Bos in 1989. In a ceremony today, the gift was to be officially accepted and placed on display in North Hall on the Calvin campus.

    The instrument was built by Wildrik Botjes, a watchmaker and goldsmith. Botjes spent 20 years building two planetaria at his home in Woldendorp in the Netherlands.

    According to Menninga, Botjes' planetaria show not only the position of the planets - with extreme accuracy - but also the date, time of day, sunrise and sunset times, true and average time, and other more esoteric information.

    In 1868, Botjes gave one of the eight-sided glass-and-wood instruments to his nephew, Botje Bos.

    When Bos moved to America in 1896, he took the planetarium - which is about one foot high and three feet in diameter - with him. Sometime later, he passed it on to his son, Hinderikus Bos.

    The younger Bos kept the instrument in good repair, and in 1926 it won first prize at an exhibit in Kalamazoo, where Bos lived.

    In 1968, Hinderikus Bos gave the planetarium to his son, Henry Bos. Though it was still operational at that time, it stopped running soon after.

    Twenty years later, Henry Bos decided to donate the museum-quality instument to the college.

    "The family recognized that there was some value in the instrument," Menninga said, "but they didn't have the time to keep it in operating condition. They are very enthusiastic supporters of Calvin. They had four kids, and all attended the school."

    The second planetarium Botjes built, Menninga said, is currently in a museum in the Netherlands.

    Menninga started the restoration last fall. He began working on it full-time about six weeks ago.

    "I tried as much as I could to keep the original materials, construction and paint," he said. "The changes that I made are the result of wear to the clock mechansim."

    Menninga taught geology at Calvin College for most of his 25 years. In 1983, when the college established a department of Geology, Geography and Environmental Studies, he was named its chairman. He remained in that position until his retirement in 1990.

    For the last two years, he has taught occasionally, worked on projects and acted as the science department's radiation safety officer.

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