[Illustration: _Frontispiece_--BUILDING AND DOME FROM SOUTH]
DEPARTMENT OF THE INTERIOR
Hon. Charles Stewart Minister
W. W. Cory, C.M.G. Deputy Minister
The
Dominion Astrophysical
Observatory
Victoria, B.C.
A sketch of the development of astronomy
in Canada and of the founding of this observatory.
A description of the building and of the
mechanical and optical details of the telescope. An
account of the principal work of the institution.
By
J. S. Plaskett, F.R.S.
Ottawa
F. A. ACLAND,
Printer to the King’s Most Excellent Majesty
1923
STAFF OF THE OBSERVATORY:
Director J. S. Plaskett, B.A., D.Sc., F.R.S.C., F.R.S.
Research Astronomer W. E. Harper, M.A.
Astronomer Reynold K. Young, Ph.D., F.R.S.C.
Astronomer H. H. Plaskett, B.A.
Secretary Miss H. R. Keay
Observing Assistant T. T. Hutchison, Esq.
THE DOMINION ASTROPHYSICAL OBSERVATORY
VICTORIA, B.C.
By J. S. PLASKETT, Director.
SECTION 1.--HISTORY AND CONSTRUCTION
Introduction
This description of the observatory, its equipment and work has been
written by the director in response to a need, frequently expressed
by the numerous visitors to the institution, of a non-technical
account of the principles of the telescope and of the work of the
institution. This account will commence by a short historical sketch
of the beginnings of the undertaking followed by a description of the
observatory and telescope and concluded by a resume of its work.
Historical Sketch
This observatory is a branch of the Department of the Interior
of the Federal Government, the department which has charge of
the administration of the western lands of the Dominion. In the
colonization of these lands, one of the obvious first needs was a
survey of the boundaries and subdivision into townships and sections.
This need led to the organization of a surveys branch of the department
and out of the necessity of accurate astronomical observations to
delimit the boundaries and define the position of the base lines
for subdivision work arose the astronomical branch. The first Chief
Astronomer of Canada, the late Dr. W. F. King, was a man of sterling
integrity and remarkable ability and to his genius must be ascribed in
large degree the present development of astronomy in Canada. As Chief
Astronomer and H. M. Commissioner of International Boundaries, he
early realized the need of an observatory for an initial meridian, for
housing and standardizing the instruments, and for some astronomical
research. He was successful in having the fine Dominion Observatory
erected on the Experimental Farm, Ottawa, in 1905 which housed the
Astronomical Branch, the staff of the International Boundary Surveys
and later the Geodetic Survey of Canada, of which he was the first
superintendent.
The Dominion Observatory was equipped with a 15-inch refractor
provided with micrometer, photometer, solar and stellar cameras,
and spectrograph. The writer was entrusted with the work with this
telescope and the spectroscopic work especially was energetically
developed and helped, with the other activities of the institution, to
bring gratifying recognition from the scientific world. The need of a
larger aperture for extending this part of the work was soon realized
by the writer and was brought to the attention of the Government.
After some delays, owing to various circumstances, it was finally
decided early in 1913 to provide a large reflector for extending
the work. Enquiries were at once made, specifications prepared and
estimates obtained from prospective makers of the instrument. Contracts
were finally awarded in October 1913 to the John A. Brashear Co. of
Pittsburgh for the optical parts and to the Warner & Swasey Co. of
Cleveland for the mechanical parts of a 72-inch reflecting telescope.
Location
It was necessary to know the location of the instrument before the
design of the mounting could be completed as the angle of the polar
axis depends upon the latitude of the site. When the new telescope
was first proposed there was no thought of locating elsewhere than at
the seat of government at Ottawa. However, upon further consideration
it was decided that the telescope should be located where, in Canada,
the best observing conditions prevailed. To determine this location
preliminary selection of five likely stations was made by the aid of
Sir Frederic Stupart, chief of the Meteorological Service from the
meteorological records. These stations, at Ottawa, at Medicine Hat,
at Banff, at Penticton, and at Victoria were occupied by Mr. W. E.
Harper, astronomer at Ottawa and the astronomical conditions were
observed by means of a 4.5-inch telescope. Victoria was unmistakably
superior in “seeing” or defining power, in low diurnal and seasonal
range of temperature and about equal so far as quantity of clear sky is
concerned. For such a large telescope as a 72-inch there could be no
question of the marked astronomical advantages of such a location, and
it was therefore decided to locate the telescope at Victoria. While the
observatory should not be in the city itself it should not be too far
away, not only on account of accessibility and facility in obtaining
supplies, but also the advantageous conditions of good seeing, low
diurnal range of temperature and small rainfall were confined to a
relatively small area near Victoria. An isolated monadnock called
locally Little Saanich Mountain but now named Observatory Hill, was
selected. This hill is about 7 miles north of Victoria and has a main
road and an interurban railway passing its base. It has an elevation of
730 feet, sufficient area around the summit for all necessary buildings
and was by far the most suitable site available.
Construction
The Provincial Government had generously agreed to give $10,000 for the
purchase of a site and to build a road to the summit. This undertaking
was fully met and the road, splendidly located and constructed and
costing over $25,000, was completed in the spring of 1915. Contracts
for the construction of the telescope pier and the circular steel
walls of the building were awarded to a local firm and this work
was completed in 1916. The revolving dome with accessories for the
operation of the telescope was made by the Warner & Swasey Co., the
builders of the telescope mounting, and was completed and erected in
1916, thus making the building ready for the telescope.
The design of the mounting was very carefully gone into by the Warner
& Swasey Co. in collaboration with the writer and was completed in the
autumn of 1914. Construction was at once begun and the mounting was
completed and temporarily erected at Cleveland in May 1916. It was then
shipped to Victoria and permanently erected in its building by November
1916.
The order for the large disc for the 72-inch mirror and for an
auxiliary flat of 55 inches diameter for testing the 72-inch was given
to the St. Gobain Glass Works of Paris by the Jno. A. Brashear Co.
as soon as the contract was awarded. The 72-inch disc was cast and
annealed by June 1914 and was fortunately shipped at once without
waiting for the 55-inch disc. It left Antwerp only about a week before
war was declared and it was only by this small margin that Canada now
has a 72-inch telescope. Grinding and polishing were at once begun
but the lack of the large flat and other difficulties delayed the
completion and it was not until April 1918, about a year and a half
after the completion of the mounting, that the figuring was finally
completed and the telescope ready for work. Nevertheless, for an
undertaking of such magnitude the work was completed in record time,
four and a half years after the awarding of the contracts.