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Astronomy and Astrophysics
Cincinnati Observatory
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Cincinnati Observatory
Cincinnati Observatory — Cincinnati, Ohio.
Exterior View of the Cincinnati Observatory, 1988.
(Photo Credit: Cincinnati Observatory)

Name:Cincinnati Observatory
Location:Cincinnati, Ohio
Classification:Public (state), buildings

Areas of Significance:National Register: education, science, NHL: science, Subtheme: physical science, Facet: astronomy

Builder:Samuel Hannaford and Sons (Observatory), Ormsby MacKnight Mitchel (Building)


The main building of the University of Cincinnati Observatory is a Georgian Revival building laid out in a "T" plan. [1] The observatory was constructed in 1873. It has a symmetrical facade distinguished by a prostyle portico with interior round fluted columns and rectangular cut rock-faced ashlar stone blocks with margins composing the corner piers and supporting a gable roof with closed pediment having a large circular window in the pediment and capped with an orb. The central entry has large rectangular doors, simple flat stone lintels and is capped with the following inscription:

Cincinnati Observatory

The windows are large and rectangular with 6/6 double hung treatment having simple stone lintels and trim with the sills forming part of a continuous string course. The open portico is reached by climbing a small series of stone steps flanked by a low stone wall. There is a raised water table composed of rock faced-ashlar and capped with a belt course. Small rectangular basement windows break the continuous foundation. The exterior walls are brick with stretcher bond treatment. The roof is highlighted by an iron balustrade with numerous balusters and interior side chimneys.

The distinguishing feature of the building is the large ribbed metal dome painted silver and resting atop a square projection where the frieze has dentils and decorative treatment. The metal dome is "open" in the respect that it protects the viewing room from rain but not from the free movement of air. When observations are conducted, it is necessary that the inside and outside temperatures be equal so as not to create air currents that would obstruct clear astronomical observation. Originally the dome was a "cheese box type," being round on the side and flat on the top. This was removed in 1895 and replaced with the existing dome.

The walls of the central rotunda serve as a series of columns to support the dome with no connection to the telescope pier, except through solid ground.

The telescope pier descends 8-1/2 feet below ground level. The pier is a cone tapered cylinder of brick, 9-1/2 feet in diameter at the base. At the top it supports the cast-iron base of the telescope mounting which is 4-1/2 by 4 feet. At no place does the building touch the central pier, so as not to transmit any vibrations to the telescope; thus the walls are independent of the telescope mounting.

At present the building houses a 16-inch refractor telescope built by Alvan Clark & Sons in 1904. The building is used for offices and has an extensive astronomy library.

O.M. Mitchel Building

The O.M. Mitchel Building, located next to the Cincinnati Observatory, is a rectangular, 5 bay by 4 bay, late Greek Revival style building designed by the Cincinnati architectural firm of Samuel Hannaford and Sons. The symmetrical facade has a portico that is distyle in antis with flat smooth stone pilasters flanking two round smooth stone columns. A small series of steps leads to double doors with an arched transom window. The doorway is surrounded by slightly decorated stone trim capped with a keystone. The stairs are flanked by rock faced ashlar stone walls that evolve into a raised water table capped by a continuous belt course.

The brick wall is composed of common bond. The windows are 1/1 double hung with flat stone voussoirs with keystone and slender stone lugsills. The corners of the building are accentuated by a decorative brick treatment. The building has a parapet entablature with dentils and capped with a low pediment with decorative finial. The parapet is capped with stone. The original portion of the building, having the larger domed turret and smaller cone turret, was built in 1904; the front part, designed to house a meeting room and library, was completed in 1908.

The O.M. Mitchel Building was constructed in 1904 to house the original 11-inch refractor installed at the Cincinnati Observatory in 1845. When originally installed in 1845 this was a 12-inch lens. Later observations confirmed suspected errors in the lens and in 1876 the lens was refigured by Alvan Clark & Sons as an 11-inch lens. The refractor is now used for night educational observations.


The Cincinnati Observatory is one of the oldest functioning observatories in the United States. Founded in 1843 it was located on Mount Adams until 1873, when it was moved to its present site on Mount Lookout, just off Observatory Avenue, in Cincinnati. The present observatory building dates from 1873.

The Cincinnati Observatory was the first fully equipped observatory in the midwest and is associated with the productive careers of such famous American astronomers as Ormsby MacKnight Mitchel (1809-1862) who published the Sidereal Messenger, the first attempt to bring astronomy to the masses in the United States, and Paul Herget (1908-1981) who was the world's foremost authority on the computation of planetary orbits.

In addition, the Cincinnati Observatory is associated with Cleveland Abbe (1838-1916), a meteorologist who began to issue daily weather bulletins in 1869. Abbe's work proved so popular with the American public that steps were taken to establish a permanent government institution to continue this service--the United States Weather Bureau.


On November 9, 1843, ex-President John Quincy Adams, 77 years old, gave the dedication address and laid the cornerstone of the observatory. The hilltop where the original observatory was located became known as Mount Adams. By June 1845 the building was complete and its telescope in place. Ormsby MacKnight Mitchel was appointed as the first director of the observatory. Under his leadership, the observatory was utilized for astronomical research and for general viewing and educational purposes. From 1843 to the start of the Civil War, the Cincinnati Observatory was reputed to be the best equipped in the United States and Mr. Mitchel stood among the notable astronomers of the world.

Having graduated from West Point in 1829, (in the class which included Robert E. Lee), Mitchel became an enthusiastic supporter of the North when the Civil War broke out. He had kept himself involved with the army since his graduation and, after several successful campaigns, became a Major General in 1862. He died that year of yellow fever.

After his death, the observatory continued with several other directors. Cleveland Abbe, director from 1868 to 1870, established a system of daily weather reports and storm predictions having secured the cooperation of observers stationed at various points throughout the country making observations at specific times and telegraphing their information to Cincinnati. Professor Abbe then used this information to issue daily weather bulletins. This service proved so popular with the public that the Federal Government initiated the United States Signal Service, headed by Professor Abbe, to continue weather observations. This work eventually led to the establishment of the United States Weather Bureau (now NOAA, the National Oceanic and Atmospheric Administration).

By 1870 the City of Cincinnati's growth and development had overtaken the once open location of the observatory and, because of smoke and other visual factors, the Mount Adams location had become unsuitable for serious astronomical research.

In 1872 the Observatory became part of the University of Cincinnati and plans were established to continue the research and educational aspects at a different location. Mr. John Kilgour, a successful businessman, donated four acres of land and $10,000 towards the construction of a new observatory and equipment. Additional funds were secured and the new observatory was erected at Mount Lookout in 1873. The original cornerstone was relaid and reads as follows:

This Cornerstone
was laid by
John Quincy Adams
Nov. 9, 1843
Removed and Relaid

On the adjoining side the stone reads:

Cincinnati Astronomical Society
May A. D. 1842

During the 20th century, the Cincinnati Observatory continued to play an important role in the history of astronomy due to its association with the productive career of astronomer Paul Herget (1908-1981), who began his work there as an assistant to the director of the observatory in 1931.

By 1931 the 11-inch and newer 16-inch refractors were not significant research instruments any longer, and the main program of the observatory was the accurate meridian-circle measurements of the positions of stars to determine their proper motions. On the recommendation of his mathematics professor, Paul Herget was hired to reduce these observations.

Paul Herget's research centered around orbit computations and the use of computer programs. Herget built his research on the work of Cincinnati mathematician Louis Brand, who emphasized the power of vectors to express complicated mathematical formulae in simple terms. Starting in 1936 Herget began to work on the determination of the orbits of the asteroids, one at a time. In his research he first used old hand-operated mechanical desk calculators, but within a few years he began to make his observations on punched cards so that all computations could be carried out on punched-card equipment.

With the advent of World War II, Herget went to work at the Nautical Almanac Office at the U.S. Naval Observatory, where he arranged for the acquisition of an IBM tabulator, summary punch, and sorter to prepare the Air Almanac. During this time Herget worked at night and in his spare time to perform the mathematical calculations for a "submarine book" for the Navy. Herget used his experience, gained at Cincinnati on the computation of orbits, to figure out a method of tracking down German submarines on patrol in the Atlantic.

By 1943 the allies had 108 listening posts around the world that could pick up enemy radio signals. Since German submarines would radio their headquarters when they sighted Allied convoys, Herget tabulated the solutions to a quarter of a million spherical triangles, needed to pinpoint the locations of submarines to within five miles. Once this information was known, destroyers could quickly locate and destroy enemy submarines. After Herget's submarine book was printed and distributed to the Navy, Allied losses to German submarines declined dramatically. This work by Herget contributed significantly to the winning of the Battle of the Atlantic during World War II.

After the war Herget returned to the Cincinnati Observatory to continue his research on the orbit computations of the minor planets and the use of computer programs. By 1947, with the support of the International Astronomical Union, Herget established the Minor Planet Center at the Cincinnati Observatory. Based upon his observations, dating back to 1939 and recorded on punched cards, Herget was able to compute the orbits of the minor planets on punched-card equipment and later on computers. From 1947 to 1978 when he retired, the Cincinnati Observatory published 4,390 Minor Planet Circulars for the larger astronomical community.

Over the years, Paul Herget became well known as an outstanding practitioner of a very specialized but highly important branch of astronomy. His orbit calculations were widely known, trusted and used. He was not only an expert at numerical computation, but a skilled theoretician with the insight necessary to cast practical astronomical problems into forms well suited for the newly emerging computer technology of the 1940s and 1950s. During his lifetime, Herget converted the Cincinnati Observatory, at a poor site, without a large telescope or significant funding, into an important research center, known throughout the world for its scientific achievements.

In 1979 the observatory formally became part of the Physics Department of the University of Cincinnati. Since that time, the observatory has remained in operation, mainly as a public facility to promote interest and understanding of astronomy through regularly scheduled public lectures and telescope viewing sessions. The 11-inch refractor that Mitchel originally installed in the observatory in 1845 and the later 16-inch refractor are used as educational tools and are enjoyed by thousands of students and visitors every year.


1. Most of the material in this form was adapted from the following sources:

Fred Mitchell, "National Register of Historic Places Inventory-Nomination Form--Observatory Historic District." (Cincinnati, Ohio: Miami Purchase Association, 1976).

Donald E. Osterbrock and P. Kenneth Seidelmann, "Paul Herget: January 30, 1908--August 27, 1981," Biographical Memoirs of the National Academy of Sciences, (Washington, DC: National Academy of Sciences, 1987), Vol. 57, pp. 59-86.

David Baab, Mike Habel and Arch Pelley, "The Cincinnati Observatory--Birthplace of the United States Weather Service." (Unpublished student paper, Historic Preservation Lab, University of Cincinnati, 1978.)

No Author, "The Historical Significance of the Cincinnati Observatory." (Unpublished paper, no date.)


Abell, George O. Exploration of the Universe. 4th ed., Philadelphia: Saunders College Publishing, 1982.

Asimov, Isaac. Eyes On The Universe. Boston: Houghton Mifflin Company, 1975.

Baab, David; Mike Habel, and Arch Pelley, "The Cincinnati Observatory--Birthplace of the United States Weather Service." Unpublished student paper, Historic Preservation Lab, University of Cincinnati, 1978.

Historical and Philosophical Society of Ohio and the University of Cincinnati, The Centenary of the Cincinnati Observatory. Cincinnati, 1944.

Kirby-Smith, H.T. U.S. Observatories: A Directory and Travel Guide. New York: Van Nostrand Reinhold Company, 1976.

Learner, Richard. Astronomy Through the Telescope. New York: Van Nostrand Reinhold Company, 1981.

Mitchell, Fred. "National Register of Historic Places Inventory-Nomination Form--Observatory Historic District." Cincinnati, Ohio: Miami Purchase Association, 1976.

No Author. "The Historical Significance of the Cincinnati Observatory." Unpublished paper, no date.

Osterbrock, Donald E., and Kenneth P. Seidelmann. "Paul Herget: January 30, 1908--August 27, 1981," Biographical Memoirs of the National Academy of Sciences. Washington, DC: National Academy of Sciences, 1987, Vol. 57, pp. 59-86.

Weddle, Kevin J. "Old Stars: Ormsby Mitchel," Sky and Telescope Magazine, January 1986, pp. 14-16.

Woodward, Charles. "Two Cincinnati Astronomers, Ormsby M. Mitchel and Paul Herget," Bulletin of the Cincinnati Historical Society, April 1966, pp. 164-87.


Cincinnati Observatory Cincinnati Observatory

Cincinnati Observatory Cincinnati Observatory

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Allegheny Observatory


Last Modified: Mon, Nov 5 2001 8:00:00 pm PDT

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