“Bite-Size Bits of Local, National, and Global History”
“Bite-Size Bits of Local, National, and Global History”
Gaithersburg in Montgomery County, Maryland — The American Northeast (Mid-Atlantic)

The Observatory

Latitude Observatory Park

The Observatory Marker image. Click for full size.
By Allen C. Browne, June 23, 2012
1. The Observatory Marker
Inscription.  U.S. Coast and Geodetic Survey Assistant, Edwin Smith or Rockville, Maryland, was assigned to oversee construction and operations at the Gaithersburg Observatory. Original plans for the Ukiah and Gaithersburg Observatories, prepared by the Central Bureau in Germany, specified that the buildings be constructed of iron. When Mr. smith learned that replicas of the Japanese and Italian Stations could not be built with the projected budget, he revised the plans,substituting wood for the specified iron.

The construction of the Gaithersburg Latitude Observatory was completed in August 1899 and it received its Zenith Telescope (ZT) in September of that same year. The facility officially opened on October 18, 1899.

The Gaithersburg Observatory was constructed with a double wall of Georgia and Virginia pine to minimize the difference between the interior and exterior temperatures; a difference that might affect the heat-sensitive Zenith Telescope. The roof was designed in two parts that move east and west on iron wheels operated manually by a rope pulley system within the building. The six-foot, six-inch full opening was always used
The Observatory Marker image. Click for full size.
By Allen C. Browne, July 15, 2012
2. The Observatory Marker
at Gaithersburg to accommodate the large Zenith Telescope. This type of telescope points at the zenith, or the direction pointing straight above a particular location. Zenith Telescopes are fitted with extremely sensitive spirit bubble levels to facilitate the accurate angle measurements required in the determination of astronomic latitude. The motion-sensitive ZT is mounted on a pier sunk into the ground to negate any vibrations transmitted from surrounding sources like traffic or trains.

The small size of the building and the esoteric character of the work that took place within speak modestly of the international importance of this landmark. The research conducted here provided all the data used in polar motion studies for decades, and fostered international cooperation that transcended the differences between nations during times of war and international strain.

From its construction in 1899 until the obsolescence of human observers forced its closing in 1982, the Gaithersburg Latitude Observatory played an integral role in the study of Earth's scientific behavior. Following its closure, the observatory remained unused and began to deteriorate. Fortunately, it was about this same time that the City of Gaithersburg formalized its historic preservation policies with the adoption of the Historic Preservation Ordinance and designated the observatory as its first officially designated historic site.

The National Oceanographic and Atmospheric Administration (NOAA) conveyed the abandoned observatory to the City for historic monument purposes in May 1987, after which the City granted an easement to the Maryland Historical Trust. Funds were secured for the observatory's restoration and on December 20, 1989, it was designated a National Historic Landmark. The Gaithersburg International Latitude Observatory, its Meridian Mark Pier, and five monuments are listed on the National Register of Historic Places.
Erected 2011 by the City of Gaithersburg.
Location. 39° 8.202′ N, 77° 11.915′ W. Marker is in Gaithersburg, Maryland, in Montgomery County. Marker is on DeSellum Avenue. Touch for map. Marker is at or near this postal address: 100 DeSellum Ave., Gaithersburg MD 20877, United States of America. Touch for directions.
Other nearby markers. At least 8 other markers are within walking distance of this marker. History and Purpose of the Gaithersburg Latitude Observatory (within shouting distance of this marker); The Meridian Mark Pier and Geodetic Survey Monuments (within shouting distance of this marker); A Night at the Gaithersburg Latitude Observatory (within shouting distance of this marker); The Chandler Wobble (within shouting distance of this marker); General Edward Braddock (approx. ¼ mile away); DeSellum Family Cemetery (approx. 0.3 miles away); Schwartz House / City Hall Built 1895 (approx. 0.4 miles away); Summit Hall Farm (approx. 0.4 miles away). Touch for a list and map of all markers in Gaithersburg.
Additional keywords. Geodesy
Categories. Science & Medicine
More. Search the internet for The Observatory.
Credits. This page was last revised on January 18, 2019. This page originally submitted on July 1, 2012, by Allen C. Browne of Silver Spring, Maryland. This page has been viewed 311 times since then and 11 times this year. Last updated on January 17, 2019, by Bruce Guthrie of Silver Spring, Maryland. Photos:   1. submitted on July 1, 2012, by Allen C. Browne of Silver Spring, Maryland.   2. submitted on July 18, 2012, by Allen C. Browne of Silver Spring, Maryland. • Andrew Ruppenstein was the editor who published this page.
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