The History of the Detroit Observatory
by Dave Snyder
Printed in Reflections: December, 1998.
Revised: September 2002
Henry Tappan (first president of the University of Michigan) wanted the University to have an observatory.
He solicited funds from some citizens of Detroit and subsequently built an observatory just outside the city limits
of Ann Arbor (it is now inside the city limits and is part of the University’s main campus). Because of the
generosity of the Detroit donors, it became known as the Detroit Observatory (even though it is not located in
The Detroit Observatory was used to conduct a variety of research including the following:
- Locating new asteroids and determining the orbits of existing asteroids.
- The discovery of two comets and the determination of the orbits of several other comets. When the Great
Comet of 1882 appeared, no one was quite sure if this was the same comet as a previously known comet or if it was
a new undiscovered comet. The observatory was used to help answer that question.
- Determining the longitude of the telescope (while we take such things for granted now, accurate determination
of longitude was a non-trivial task at the time).
- Construction of lunar tables.
- The search for Vulcan. In the 1800’s certain irregularities in the orbit of Mercury could not be explained
by Newton’s Law of Gravitation. Some years earlier similar irregularities in the orbit of Uranus had been
resolved by assuming an unseen body was responsible for perturbations. Therefore astronomers speculated that
another new planet must exist that would explain the orbit of Mercury and this planet was given the name Vulcan.
The search for Vulcan became an obsession of Watson, one of the directors of the observatory. However, the
real solution to Mercury’s orbit would wait until 1915: General Relativity correctly predicts the orbit of Mercury
without resorting to unseen planets. At present there is no evidence for Vulcan and it probably does not
- Determination of the aberration constant.
- Obtaining the spectrographs of stars (and other unspecified star observations).
- In addition to astronomical observations, weather observations were made at the observatory (for a while the
observatory was a station of the U. S. Weather Service).
There are records of several expeditions conducted by different directors. These expeditions were to various
locations in the U. S. and other countries, mainly to observe solar eclipses (solar eclipses are only visible from
specific locations so you need to travel in order to see the eclipse).
At the beginning (with occasional exceptions) students and the general public were denied access to the observatory.
There were complaints. The complaints seem to end around 1878 with a change in directors and when a separate
building (later known as the Student’s Observatory) was constructed.
The observatory (now located between several dormitories and a block away from the University Medical Center)
eventually became unsuitable for research. It is one of the oldest observatories in the United States that
is still standing and has been recently renovated.
An chronology of events follows:
- 1852 - Henry Philip Tappan was selected as the first president of the University of Michigan. He began
his term with a vision of the University that included not only the traditional classical course but also a scientific
course. Astronomy was needed to complete the scientific course, and to this end Tappan felt that an observatory
was essential. Classes in astronomy had been taught prior to 1852, but they were limited and the University
owned no telescopes or other equipment. He stated this vision and a request for help to achieve that vision
in his inaugural address. One of people listening to this appeal was Henry S. Walker, a businessman from
Detroit. Tappan and Walker began a discussion which resulted in a fundraising effort which lead to 29 donors.
Most of these donors were businessmen, lawyers, bankers and politicians from Detroit. Walker was the most
generous of this group (part of their interest was the desire for an accurate time standard and an observatory
could help create such a standard). Because of this generosity, the plans for the observatory extended past
what had been envisioned by Tappan. In recognition of the role the city of Detroit played, the name “Detroit
Observatory” was used for this building in honor of the donors. However this name was never officially
adopted by the University. A 12” refractor was ordered (to be built by Henry N. Fitz) along with a sidereal
clock and a meridian circle.
- 1853 - The original plan was for the observatory to be built in the center of campus, but finally a site was
selected just outside the city limits on a hill a half mile from campus. (Since then, both the city and the
university have grown: this site is now inside the city limits and is part of the central campus). Many people
(including Tappan) were unhappy with this site. In spite of numerous relocation attempts over the years,
the observatory remains at the same location to this day. Later in the year construction was begun.
- 1854 - The first director of the observatory arrived, Franz F. E. Brünnow (from Prussia). In addition
to running the observatory, Brünnow also was responsible for teaching astronomy students and brought mathematical
techniques into the study of astronomy. The number of students was small, in fact one class had a single
student. This student, James Craig Watson, was an exceptional observer and would take more responsibility
of the observatory in the next few years. Brünnow later wrote that it would have better if the building
had been completed before he arrived.
- 1854 - The original building was completed including a 23 foot dome which would soon house the 12” refractor
(this is the first observatory built in Michigan). The 12” refractor arrives, but is removed and a replacement
is ordered. Another room housed the meridian circle. This telescope viewed the sky through panels in
the roof, the north wall and the south wall. These panels could be opened and closed as needed. An
additional funding drive was begun. With the exception of the 12” telescope itself, all the equipment
had arrived including a meridian circle and a sidereal clock. The former was referred to as the “Walker
meridian circle” after Henry S. Walker. A 4” comet seeker telescope was ordered.
- 1855 - Fitz acknowledged that the telescope would arrive late and loaned the University another telescope.
The 12” telescope originally ordered arrived, but Brünnow did not find the mount acceptable.
- 1856 - Brünnow returns the unacceptable 12”. The observatory was operational. There was
still a debt, but Tappan raised enough additional funds to pay off the debt.
- 1857 - Fitz made another 12” telescope that was accepted. It was equipped with a variety of eyepieces,
a 2” finder and had an equatorial mount. A road was built from the city of Ann Arbor to the observatory
(this road still exists and is called “Observatory Street”).
- 1858 - The citizens of Detroit asked for information on how time signals could be transmitted from the observatory
to the city of Detroit. Time signals probably were first transmitted by telegraph in the year 1861 (the exact
date is uncertain). Brünnow appoints Watson to Assistant Director.
- 1859 - Brünnow resigns and Watson was left in charge. The regents allow Brünnow to retain the
title of Director of the Observatory but he is given no pay. Brünnow took the directorship of Dudley
Observatory in New York.
- 1860 - An attempt is made to get Brünnow to return. He accepted (he received a significant increase
in salary). A chronograph arrives (this is a device that records the position of stars as they cross the
- 1861 - The longitude of the observatory accurately determined.
- 1863 - Tappan is dismissed by the Regents. Shortly afterwards, Brünnow resigns and returns to Germany.
Watson officially becomes director of the observatory. Watson announces a series of “open houses”,
but only a few were held. Between 1863 and 1877, Watson discovers 22 asteroids, all but one of which were
discovered using the telescope at the Detroit Observatory.
- 1868 - A large addition was added to the observatory. This was used as a residence for the observatory
director (it was built in spite of a plan to relocate the observatory).
- 1869 - Watson travels to Iowa to view a solar eclipse.
- 1874 - Watson takes a year long leave of absence and travels to Asia, Europe and Egypt.
- 1878 - Watson took a trip to Wyoming to observe a solar eclipse. Watson took the opportunity to look
for Vulcan, a planet that supposedly exists inside the orbit of Mercury. In the process he thought he discovered
one and possibly two such planets. By all accounts Watson was a careful observer, but no one else was able
to corroborate these observations. The scientific community was skeptical.
- 1878 - Watson resigns as director. A small building was constructed a hundred feet from the main building
which was used by the U. S. Government to observe the transit of Mercury in 1879. This building was later
remodeled and became the “Student’s Observatory” as an attempt to end complaints about access to main
- 1879 - Mark Harrington accepts the position as director of the observatory. Much of Harrington’s work
involved meteorology, not astronomy. Courses in meteorology were offered.
- 1880 - A set of meteorological instruments were installed so that weather observations could be conducted at
the observatory. A 6” equatorial refractor and a 3” transit were added to the equipment at the
Student’s Observatory. Comet Schaeberle II was discovered at the Detroit Observatory.
- 1881 - Comet Schaeberle IV was discovered at the Detroit Observatory.
- 1882 - The Great Comet of 1882 was observed and the orbit was determined to see if was the same comet as an
- 1891 - Harrington left on a leave of absence and William Joseph Hussey was made acting director. The meteorology
courses were dropped. Harrington never returned, but over the next eight years held other positions including
president of the University of Washington and director of the Weather Bureau at San Juan, Puerto Rico.
- 1892 - Hussey resigns so he can go to Stanford University. Asaph Hall, Jr. becomes director of the observatory.
During Hall’s directorship, a portion of the telescope time was given to ornithologists who were studying bird
migration. Various equipment were refurbished.
- 1898 - Harrington retires due to failing health (both physical and mental).
- 1902 - A sextant was purchased.
- 1903 - A surveyor’s transit was purchased.
- 1904 - Hall publishes Determination of Aberration Constant. The work related to this was done
at the Detroit Observatory.
- 1905 - Hall resigns. Hussey returns to Ann Arbor to become director of the observatory. While he
was gone Hussey had done work on a variety of subjects including double stars. Double stars would occupy
much of Hussey’s work. In the beginning Hussey was the only professor of astronomy but during Hussey’s term
of office, the size of the department grew dramatically. Directors residence was enlarged and the observatory
shop was started.
- 1907 - The 12” refractor underwent extensive reconstruction. A 3½” finder, a new driving
clock and other enhancements were added.
- 1907 - A 37½” mirror was acquired.
- 1908 - The Student’s Observatory was moved three hundred feet to the west. This made room for improvements
to the main building.
- 1908 - A new 4½” comet seeker was mounted on the observatory director’s residence (the original
comet seeker was used as a finder for the 37½”). Various improvements were made to the Student’s
- 1909 - An extension to the main building was completed (except for the dome which was not completed until the
next year). This included a classroom, a clock room and a photographic room. Various seismological
equipment were installed in the basement.
- 1910 - A new 44 foot dome was completed to accommodate a new 37½” reflector.
- 1911 - Hussey sails to Argentina to discuss an offer of the directorship of La Plata Observatory. As
a result he becomes the director of La Plata and continues as director of the Detroit Observatory. Hussey
had a goal of setting up a new observatory in the southern hemisphere, and this was the first step. The 37½”
telescope was installed in the dome constructed in 1910.
- 1912 - Expansion of the University began to encroach on the observatory. This encroachment included a
proposed power plant. There was concern that
emissions from the power plant would distort observations.
The power plant was constructed sometime later.
- 1915 - A new hospital was to be built to the north of the observatory. Lights from this hospital would
interfere with observations. The hospital was constructed sometime later.
- 1922 - There was a proposal to build a dormitory for nurses (known as “Couzen’s Hall”) to the west
of the observatory.
Emissions from the power plant and increased light pollution made the
observatory less effective and new construction like this dormitory
would only make matters worse.
The need to do something about these encroachments seemed “urgent,” but no
action was taken. Improvements were made to the 37½”.
- 1923 - Couzen’s Hall was constructed after the Student’s Observatory (which was in the way) was torn down.
- 1923 - The 37½” reflector was overhauled and two new pieces of equipment were constructed: a spectrograph
and a spectrocomparator.
- 1924 - Land near Portage Lake considered as a replacement for the observatory (see Portage
- 1925 - Hussey attempts to observe a solar eclipse in a balloon, but weather conditions prevent any observations
(see the McMath-Hulbert Observatory). A 27” refractor was
built in Ann Arbor (it was set up on the lawn of the observatory for testing) and subsequently sent to a soon to
be opened observatory in South Africa (see Lamont-Hussey Observatory).
- 1926 - Harrington dies. Hussey unexpectedly becomes ill and dies. Ralph Hamilton Curtiss becomes
- 1927 - Curtiss becomes director of the observatory. The university opens an observatory to replace the Student’s
Observatory in a classroom building on the main campus (see the Angell Hall
- 1928 - Hussey’s goal to have an observatory in the southern hemisphere is finally realized after his death
when the University opens a new observatory in South Africa (see the Lamont-Hussey
Observatory). Between the Detroit Observatory and the Angell Hall Observatory there were 1,194 visitors
during the school year. (This compares with 2,606 visitors at the Lamont-Hussey Observatory the same year).
- 1929 - Curtiss died of a serious illness and Will Carl Rufus became acting director.
- 1930 - Heber Doust Curtis becomes director of the observatory.
- 1930 - Two businessmen and a judge open an observatory in Pontiac (see the McMath-Hulbert
Observatory). Curtis develops a strong relationship with this new observatory.
- 1931 - The name “Detroit Observatory” gave the wrong impression about the location of the building,
so the regents formally dropped the name (even though it had never been approved) and approved the name “Observatories
of the University of Michigan.” This includes what had been known as the Detroit Observatory, the Angell
Hall Observatory, the Lamont-Hussey Observatory and the McMath-Hulbert Observatory. However most people still
refer to the original observatory by the name “Detroit Observatory.”
- 1936 - The telescope mirror was aluminized, improving its efficiency.
- 1941 - W. Carl Rufus becomes director.
- 1945 - Alan D. Maxwell becomes acting director.
- 1946 - Leo Goldberg becomes director.
- 1946 - The residence was divided into three apartments.
- 1950 - The university opens a new observatory 15 miles northwest of Ann Arbor (see the Portage
- 1953 - Since the observatory is now in the middle of the city (and thus exposed to significant amounts of light
pollution) and better observatories were available elsewhere, there was sentiment to close the observatory.
This action was deferred.
- 1954 - The observatory residence (constructed in 1868) was torn down.
- 1955 - The university opens another observatory near the Portage Lake Observatory (see the Peach
- 1960 - Freeman D. Miller becomes acting director.
- 1961 - Orren C. Mohler becomes director.
- 1963-1994 - In 1963, the University asked the department to move its offices and equipment out of the Detroit
Observatory. The telescope was never moved, but the rest of the equipment was relocated. Most faculty
members moved their offices from the observatory into the newly constructed Dennison Building (also known as Physics-Astronomy
During the 1970’s, plans were developed to demolish the observatory, however a number of individuals fought
to preserve it. Despite lack of funds from the University, both Al Hiltner (then chair of the Astronomy Department)
and Orren Mohler continued to make use of the observatory (a building that is actively used is easier to preserve).
In addition, a group of people lead by attorney John Hathaway succeeded in getting the observatory listed in the
National Registry of Historic Places.
The 1908 addition had become unsafe and the University decided to tear it down. There was general agreement
that this was the correct thing to do, however there was not agreement on what to do with with the original observatory
(the only part of the building which remained). A committee consisting of Al Hiltner, Orren Mohler, Margo
McGuinnis and Nick and Margaret Steneck (among others) was formed with the agenda of saving the observatory.
Without this effort the building probably would have been demolished.
In time, a few groups made regular use of the observatory including the University Lowbrow Astronomers (a newly
formed astronomy club). The Lowbrows held their monthly meetings in the building until 1994.
The fact that the building was being used convinced the University to assist in maintaining the building.
However most of the effort to maintain the building was done without University funds.
- 1970 - W. Albert Hiltner becomes director of the Observatory.
- 1976 - The 1908 addition was torn down. With all the additions removed, only the 1854 building remained.
- 1994-1996 - Jim and Anne Duderstadt took an interest in preservation of the observatory (Jim Duderstadt was
University President at the time). The Office of the Vice President for Research took responsibility for
the building and funds were made available for its restoration. Groups (such as the Lowbrows) that had been
using the building made alternate arrangements so restoration could commence. The Detroit Observatory Advisory
Committee was formed in 1994 by Homer Neal. This committee consisted of Patricia Whitesell (Chair), Anne
Duderstadt, William J. Hennessey, Robert Warner, and Patrick Seitzer. The committee reported to the Vice
President for Research and continued until October 1998.
A separate subcommittee on the Telescopes and Instruments was formed to work on the instruments within the observatory.
The chair was Patrick Seitzer (astronomy) and the other members were Rudi Lindner (history), Nick Steneck (history),
Dick Teske (astronomy), and Gary Bernstein (astronomy). This committee existed till October of 1998 as well,
and discussed in great detail whether to restore the telescope to as it was in 1908 (Hussey’s telescope), or attempt
to recreate the wooden tube from Fitz’s original telescope. The committee decided (not unanimously) to go
back to the 1908 telescope, largely because there was not enough information at hand to recreate the wooden tube.
Chris Ray was retained to do all the mechanical work and did so in the fall of 1997. The lens was removed
(by Pat Seitzer) and taken to the Art Museum for storage. As of October 1998, it was still there.
There were two student members of the committees as well. The first was Ken Banas, who after he graduated
was followed by Dale Kocevski. Both were concentrators in astronomy.
- 1996-1999 - Patricia Whitesell oversaw the restoration of the observatory and many pieces of equipment as
well. In particular, the Fitz 12” telescope was fully restored to its 1907 condition. The architect
for the restoration was Quinn Evans and the contractor was J. C. Beal Construction, inc.
- September 1999 - The restoration is complete and a set of
open houses have been scheduled for the observatory.
The first photograph shows the east side of the Observatory as seen from Observatory Street and was taken in October 1999, after the restoration was complete. The second photograph shows the north side of the Observatory as seen from Ann Street and was taken in
April 2002 (a horse chestnut tree partially obscures the observatory dome). Both photographs were taken by Dave Snyder.
Detroit Observatory Links
Asaph Hall, Sr. (Postgraduate work in Astronomy at University of Michigan,
- Deimos (Asaph Hall, Sr. discovered
Deimos in August of 1877).
- Phobos (Asaph Hall, Sr. discovered
Phobos a few days later).
Heber D. Curtis (Director of the Observatory between 1930-1941).
Copyright © 2015, the University Lowbrow Astronomers. (The University Lowbrow Astronomers are an amateur astronomy club based in Ann Arbor, Michigan).
This page originally appeared in Reflections of the University Lowbrow Astronomers (the club newsletter).
This page revised Tuesday, April 10, 2018 7:08 PM.
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