Observatory under construction

Construction of the Dominion Observatory, Ottawa (ca. 1904). These images are from a group of archival photos that came from the Observatory´s own collection.

CHIN
Canadian Heritage Information Network, Canada Museum of Science and Technology, Musée de la civilisation, Stewart Museum, Canadian Medical Hall of Fame, Museum of Health Care at Kingston, University Health Network Artifact Collection, University of Toronto Museum of Scientific Instruments, University of Toronto Museum Studies Program, Suzanne Board, Dr. Randall C. Brooks, Sylvie Toupin, Ana-Laura Baz, Jean-François Gauvin, Betsy Little, Paola Poletto, Dr. James Low, David Kasserra, Kathryn Rumbold, David Pantalony, Dr. Thierry Ruddel, Kim Svendsen

© 2008, CHIN. All Rights Reserved.


The Dominion Observatory (DO) was established in part to provide the most accurate time possible. The time at a prime meridian is key to determining longitude and, as Greenwich had become the prime meridian for the World, the DO in Ottawa became the prime meridian of Canada in 1905. All surveys in Canada referred back to the observatory.

Determining time required a transit telescope to observe the moment a star crossed ("transited") the north/south line of the sky (the meridian). Several transit telescopes have been used at the DO and the one shown is one of the smaller. However, time was not the only responsibility of the new observatory. The government had appropriated $375,000 for the facility, which was to include a 15-inch refracting telescope. This was intended not to determine time, but for astrophysical studies.

The surfaces of the two elements that made up the 15-inch lens were accurate to a millionth of an inch. The original lens was replaced in 1958 with a triple element lens, still the largest of its type ever fabricated.

The telescope was originally housed in a copper covered dome at the Central Experimental Farm (CEF) in O Read More
The Dominion Observatory (DO) was established in part to provide the most accurate time possible. The time at a prime meridian is key to determining longitude and, as Greenwich had become the prime meridian for the World, the DO in Ottawa became the prime meridian of Canada in 1905. All surveys in Canada referred back to the observatory.

Determining time required a transit telescope to observe the moment a star crossed ("transited") the north/south line of the sky (the meridian). Several transit telescopes have been used at the DO and the one shown is one of the smaller. However, time was not the only responsibility of the new observatory. The government had appropriated $375,000 for the facility, which was to include a 15-inch refracting telescope. This was intended not to determine time, but for astrophysical studies.

The surfaces of the two elements that made up the 15-inch lens were accurate to a millionth of an inch. The original lens was replaced in 1958 with a triple element lens, still the largest of its type ever fabricated.

The telescope was originally housed in a copper covered dome at the Central Experimental Farm (CEF) in Ottawa. The astronomers had a variety of instruments at their disposal including a prism spectrograph, cameras and filar micrometer for measuring stellar positions.

The building and dome still exist at the CEF, but after the Dominion Observatory closed in 1970, the telescope was moved to the Canada Science and Technology Museum. It remains the largest refractor ever erected in Canada.

© 2001, CHIN. All Rights Reserved.

Transit telescope

Astronomical transit telescope used at the Dominion Observatory. It was designed to flip 180 degrees so that alignment errors of the base were averaged. Used to time the passage of stars across the meridian in order to regulate Canada´s master clocks. Canada Science and Technology Museum

Troughton & Simms, London, England
Canadian Heritage Information Network, Canada Museum of Science and Technology, Musée de la civilisation, Stewart Museum, Canadian Medical Hall of Fame, Museum of Health Care at Kingston, University Health Network Artifact Collection, University of Toronto Museum of Scientific Instruments, University of Toronto Museum Studies Program, Suzanne Board, Dr. Randall C. Brooks, Sylvie Toupin, Ana-Laura Baz, Jean-François Gauvin, Betsy Little, Paola Poletto, Dr. James Low, David Kasserra, Kathryn Rumbold, David Pantalony, Dr. Thierry Ruddel, Kim Svendsen
1900 - 1920
700217
© 2008, Canada Science and Technology Museum. All Rights Reserved.


Refracting telescope

The 15-inch refracting telescope ca. 1930. Note the observer´s ladder. Used to study astronomical objects under moderately high magnification. Canada Science and Technology Museum

Warner & Swasey Ltd., Cleveland, Ohio
Canadian Heritage Information Network, Canada Museum of Science and Technology, Musée de la civilisation, Stewart Museum, Canadian Medical Hall of Fame, Museum of Health Care at Kingston, University Health Network Artifact Collection, University of Toronto Museum of Scientific Instruments, University of Toronto Museum Studies Program, Suzanne Board, Dr. Randall C. Brooks, Sylvie Toupin, Ana-Laura Baz, Jean-François Gauvin, Betsy Little, Paola Poletto, Dr. James Low, David Kasserra, Kathryn Rumbold, David Pantalony, Dr. Thierry Ruddel, Kim Svendsen
1903 - 1905
740488
© 2008, Canada Science and Technology Museum. All Rights Reserved.


Achromatic telescope lens

Creates magnified images of astronomical objects. Original two-element objective lens for the 15-inch telescope by John Brashear, one of the top opticians in the world for refracting telescopes. It is designed to correct chromatic aberration of star images--without such correction the stars would exhibit coloured fringes. Canada Science and Technology Museum

John A. Brashear Co. Ltd., Pittsburgh, PA
Canadian Heritage Information Network, Canada Museum of Science and Technology, Musée de la civilisation, Stewart Museum, Canadian Medical Hall of Fame, Museum of Health Care at Kingston, University Health Network Artifact Collection, University of Toronto Museum of Scientific Instruments, University of Toronto Museum Studies Program, Suzanne Board, Dr. Randall C. Brooks, Sylvie Toupin, Ana-Laura Baz, Jean-François Gauvin, Betsy Little, Paola Poletto, Dr. James Low, David Kasserra, Kathryn Rumbold, David Pantalony, Dr. Thierry Ruddel, Kim Svendsen
1904 - 1905
751087
© 2008, Canada Science and Technology Museum. All Rights Reserved.


Filar micrometer

Filar micrometer from the 15-inch telescope was used for measuring the diameters of planets and the separation and angles between double stars. This allowed their orbits to be determined over many years of observations. Fine wires adjusted with a precisely-made screw allow accurate diameter, position and separation measurements. Canada Science and Technology Museum

Warner & Swasey Ltd., Cleveland, Ohio
Canadian Heritage Information Network, Canada Museum of Science and Technology, Musée de la civilisation, Stewart Museum, Canadian Medical Hall of Fame, Museum of Health Care at Kingston, University Health Network Artifact Collection, University of Toronto Museum of Scientific Instruments, University of Toronto Museum Studies Program, Suzanne Board, Dr. Randall C. Brooks, Sylvie Toupin, Ana-Laura Baz, Jean-François Gauvin, Betsy Little, Paola Poletto, Dr. James Low, David Kasserra, Kathryn Rumbold, David Pantalony, Dr. Thierry Ruddel, Kim Svendsen
c. 1905
700212.2
© 2008, Canada Science and Technology Museum. All Rights Reserved.


At the same time as the 15-inch telescope was installed, the DO acquired a large coelostat, a telescope specifically designed for observation of the Sun, at the CEF. From around 1930 to 1936, solar astronomer Ralph DeLury undertook a series of photos of the Sun. These were measured to determine the rate at which sunspots traverse the solar disc. It was found that the rate of rotation at the solar equator was greater than at the poles by several days.

In analyzing the images, DeLury had to correct for foreshortening, an effect where the spots coming or disappearing around the Sun’s edge appear to move more slowly. This is a geometrical effect that can be mathematically calculated. To speed the process (remember this is long before electronic computers) DeLury had the Observatory’s shops construct an analogue computer. This consisted of a globe made of polished steel with lines of latitude and longitude engraved on it. Using the photographic negatives, he then simply projected the solar images onto the globe and read off the angles of latitude and longitude for each of the sunspots he was studying.

At the same time as the 15-inch telescope was installed, the DO acquired a large coelostat, a telescope specifically designed for observation of the Sun, at the CEF. From around 1930 to 1936, solar astronomer Ralph DeLury undertook a series of photos of the Sun. These were measured to determine the rate at which sunspots traverse the solar disc. It was found that the rate of rotation at the solar equator was greater than at the poles by several days.

In analyzing the images, DeLury had to correct for foreshortening, an effect where the spots coming or disappearing around the Sun’s edge appear to move more slowly. This is a geometrical effect that can be mathematically calculated. To speed the process (remember this is long before electronic computers) DeLury had the Observatory’s shops construct an analogue computer. This consisted of a globe made of polished steel with lines of latitude and longitude engraved on it. Using the photographic negatives, he then simply projected the solar images onto the globe and read off the angles of latitude and longitude for each of the sunspots he was studying.


© 2001, CHIN. All Rights Reserved.

Coelostat shed

The Coelostat shed was used to photograph the Sun. The coelostat was first erected in Labrador (bottom) for the total solar eclipse in 1905 but the event was clouded out. It was then mounted in its own shed in Ottawa (top) and used to monitor solar activity from 1905-ca. 1965. Canada Science and Technology Museum

Warner & Swasey, optics John Brashear
Canadian Heritage Information Network, Canada Museum of Science and Technology, Musée de la civilisation, Stewart Museum, Canadian Medical Hall of Fame, Museum of Health Care at Kingston, University Health Network Artifact Collection, University of Toronto Museum of Scientific Instruments, University of Toronto Museum Studies Program, Suzanne Board, Dr. Randall C. Brooks, Sylvie Toupin, Ana-Laura Baz, Jean-François Gauvin, Betsy Little, Paola Poletto, Dr. James Low, David Kasserra, Kathryn Rumbold, David Pantalony, Dr. Thierry Ruddel, Kim Svendsen
1904 - 1905
Ottawa, Ontario, CANADA
Newfoundland and Labrador (except Avalon Peninsula), CANADA
660402
© 2008, Canada Science and Technology Museum. All Rights Reserved.


Solar Globe

Used to geometrically measure the latitude and longitude positions of spots on the Sun´s surface. DeLury´s globe was used to make direct measurement of sunspots´ positions using images projected onto the globe. Programmable calculators were thirty-five years in the future! The four solar images were taken over several days in August 1930. Note the dark sunspot moving right to left due to the Sun´s rotation. Canada Science and Technology Museum

Dominion Observatory, Ottawa
Canadian Heritage Information Network, Canada Museum of Science and Technology, Musée de la civilisation, Stewart Museum, Canadian Medical Hall of Fame, Museum of Health Care at Kingston, University Health Network Artifact Collection, University of Toronto Museum of Scientific Instruments, University of Toronto Museum Studies Program, Suzanne Board, Dr. Randall C. Brooks, Sylvie Toupin, Ana-Laura Baz, Jean-François Gauvin, Betsy Little, Paola Poletto, Dr. James Low, David Kasserra, Kathryn Rumbold, David Pantalony, Dr. Thierry Ruddel, Kim Svendsen
c. 1936
950947, 940228
© 2008, Canada Science and Technology Museum. All Rights Reserved.


Learning Objectives

The learner will:
  • Identify and appreciate the way history and culture shape a society’s science and technology
  • Describe scientific and technological developments, past and present, and appreciate their impact on individuals and societies
  • Appreciate the contribution of Canadians to the field of astronomy on the global stage

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