Editing David Dunlap Observatory (section)

===Construction===
[[File:Construction of Dunlap Observatory dome.jpg|thumb|Construction of the observatory's dome in [[Newcastle upon Tyne]], after which it was dismantled and shipped to Richmond Hill]]
[[File:Mirror installation at observatory.jpg|thumb|Installation of the mirror]]
[[File:Queue at the Dunlap Observatory.jpg|thumb|Queue at the observatory in 1935, when guests were invited to inspect the telescope]]
Chant immediately ordered a telescope, selecting a {{convert|74|in|m|adj=on}} instrument from [[Sir Howard Grubb, Parsons and Co. Ltd.|Grubb, Parsons and Company]] in England. This would make it the second-largest telescope in the world, second only to the {{convert|100|in|m|adj=on}} instrument at [[Mount Wilson Observatory]].{{sfn|Russell|1999}} It was, however, only slightly larger than the one that had recently gone into service for the [[Dominion Astrophysical Observatory]] in British Columbia, at {{convert|72|in|m}}. The eighty-ton sixty-one-foot (18.6&nbsp;m) copper dome and cylindrical walls of the observatory building were constructed by the [[Cleveland Bridge & Engineering Company|Cleveland Bridge and Engineering Co.]] of Darlington, UK, with the mechanical parts supplied by Grubb & Parsons. The parts of the building and telescope arrived in Toronto in 1933 and were reassembled on site. The administration building, a few hundred feet from the main observatory, was designed by Toronto architectural firm Mathers & Haldenby. The {{convert|76|in|m|adj=on}} mirror blank (the two outermost inches (5&nbsp;cm) of the mirror are not used) was supplied by [[Corning Incorporated]] and cast in [[Pyrex]] from a batch of glass that Corning also used to produce the {{convert|200|in|m|adj=on}} mirror for [[Palomar Observatory]]. Chant and Mrs. Dunlap attended the pouring of the mirror at the factory in [[Corning (city), New York|Corning, New York]] in June 1933. The mirror was [[Annealing (materials science)|annealed]], then shipped to Grubb-Parsons in England for [[polishing]]. The telescope was completed in time for the finished mirror's return in May 1935.{{sfn|Russell|1999}}<ref>{{cite news |url=https://www.yorkregion.com/opinion-story/5594856-u-of-t-didn-t-let-town-buy-observatory/|title=U. of T. didn't let town buy observatory |publisher=Richmond Hill Liberal |date=30 April 2015}}</ref>

The official opening was on 31 May 1935, Chant's 70th birthday. The [[opening ceremony]] was attended by notables including [[Frank Watson Dyson|Sir Frank Dyson]], former [[Astronomer Royal]], and former Prime Minister [[William Lyon Mackenzie King]], who praised the Observatory as "a gift to science all over the world". [[Reynold K. Young]] was named the first director of the DDO.{{sfn|Russell|1999}} Chant retired the same day and moved into Observatory House, the original pre-[[Canadian Confederation|Confederation]] [[farmhouse]] (built in 1864 for Alexander Marsh and known also as Elms Lea Alexander Marsh<ref>{{cite web |url=https://www.flickr.com/photos/yorkregiongovt/34310554743 |title=Elms Lea Alexander Marsh House |website=Flickr.com |date=March 2017 |access-date=31 July 2019}}</ref>) just to the south of the administration buildings, where he spent his remaining years. In May 1939, the train carrying [[King George VI]] and [[Queen Elizabeth, the Queen Mother]] on their cross-Canada tour paused on the railway below the observatory, the largest telescope in the commonwealth.<ref>"[http://www.richmondhill.ca/documents/meetings/cow/6_17_2008_16_30/item%2012.pdf Scheinman Report] {{webarchive|url=https://web.archive.org/web/20110525204450/http://www.richmondhill.ca/documents/meetings/cow/6_17_2008_16_30/item%2012.pdf |date=2011-05-25 }}", ''Town of Richmond Hill'', 17 June 2008, SRPD.08.097</ref>

Grubb-Parsons built four more 1.88-metre telescopes with similarities to the instrument in Richmond Hill: for [[Radcliffe Observatory]] near Pretoria, [[Mount Stromlo Observatory]] in Australia, [[Helwan]] Observatory in Egypt, and an observatory in [[Okayama Prefecture]] in Japan.<ref>{{cite web |url=http://www.oao.nao.ac.jp/en/ |title=Okayama Astrophysical Observatory, NAOJ|access-date=31 July 2019}}</ref> The South African instrument was disassembled and moved to [[Sutherland, Northern Cape]] in the 1970s because of light pollution.<ref>[http://www.saao.ac.za/assa/html/his-obs-radcliffe.html Assa Historical Section<!-- Bot generated title -->] {{webarchive|url=https://web.archive.org/web/20090628002350/http://www.saao.ac.za/assa/html/his-obs-radcliffe.html |date=28 June 2009 }}</ref> The original telescope mirror at Helwan was replaced by Zeiss in 1997, and the telescope at Mount Stromlo was destroyed by fire in 2003.<ref>{{cite web |url=http://rsaa.anu.edu.au/about-us/history |title=History |website=Research School of Astronomy & Astrophysics, Australian National University |access-date=12 February 2015 |archive-url=https://web.archive.org/web/20180319091429/http://rsaa.anu.edu.au/about-us/history |archive-date=19 March 2018 |url-status=dead }}</ref> A 1.93-metre Grubb-Parsons telescope at [[Haute-Provence Observatory]] with a higher-resolution [[Optical spectrometer|spectrograph]] was used to discover an [[Exoplanet|extrasolar planet]] orbiting the star [[51 Pegasi]] in 1995.<ref>{{cite conference |last1=Mayor |first1=M |last2=Queloz |first2=D |url=http://www.obs-hp.fr/www/pubs/Coll51Peg/51peg_p1-10.pdf |title= The discovery of 51 Pegasi at Haute-Provence Observatory |pages=1–10 |book-title=Tenth Anniversary of 51 Peg-b: Status of and prospects for hot Jupiter studies |editor=Luc Arnold |editor2=François Bouchy |editor3=Claire Mouton}}</ref>

The three smaller domes at the top of the DDO administration building are used for smaller instruments. Soon after the observatory opened in 1935, a {{convert|50|cm|in|adj=on}} [[Cassegrain reflector]] telescope was installed in the southern dome. A large vacuum tank was constructed, then used to [[aluminize]] the 74-inch mirror in 1941.<ref>{{cite journal
 | title=Aluminizing Tank for the David Dunlap Observatory (with Plates I-III)
 | last=Young | first=R. K.
 | journal=Journal of the Royal Astronomical Society of Canada
 | volume=36 | page=1 | date=January 1942
 | bibcode=1942JRASC..36....1Y }}</ref> The {{convert|6|in|mm|adj=on}} Cooke Refractor had been out of use since the Meteorological Office had given it to [[Hart House (University of Toronto)|Hart House]], but it was little used and was moved into the northern dome in 1951 to be used by undergraduates. In 1965, a similar {{convert|60|cm|in|adj=on}} Cassegrain was added to the central dome.{{sfn|Russell|1999}}