Each year we try to do something of interest and often of a historical nature for the Citroen Autoclub Canada Spring outing. On May 7, 2016 our outing the David Dunlap Observatory achieved both objectives well beyond the expectations of those that attended. In all 28 members came out for a tour of the observatory and then a drive north of the greater Toronto area over to the Forks of the Credit river near the town of Belfountain. We met at the McDonalds restaurant on 16th Ave. close to the observatory which was out first stop.
See a full photo gallery of the event here: 
George Dyke had arranged a private tour for the Club. The observatory portion was conducted by Paul Mortfield, Chair of the DDO Committee. His 30 minute walkabout included showing us how the building was constructed and how it operates. Constructed in the early 1930’s, the entire building and the telescope were built in England and shipped over to Canada. The 61’ in diameter building is a metal structure weighing 80 tons whose framework and skin had to be reassembled in its present Richmond Hill Ontario location. Only the concrete structure acting as the base for the telescope was poured locally and that goes 5 stories into the ground to bedrock so the telescope does not vibrate due to trains passing about a km away, or from anything else for that matter!
The telescope’s support and the dome that covers it all have rotation ability which is all done with gears, pulleys and electric motors that are original from the 1930’s. The dome rotates on a circular rail, rolling on 8 steel train wheels pulled by a giant cable that runs around the dome’s perimeter. The cable is counter balanced and geared so a single electric motor can rotate it in perfect sync with the telescope itself as it tracks with the rotation of the earth.
The telescope, weighing 23 tons (without its primary mirror), is perfectly balanced and can be positioned to observe parts of the galaxy by just one person turning two large circular handles with relative ease, as Paul demonstrated. Once fixed on a star, another very small electric motor engages a complex array of gears to assure the telescope remains locked on its target as the earth rotates. The observatory is at latitude 43.8619° N so the telescope must be able to stationary track. Thus it moves both horizontally and vertically.
The electrical system is equally fascinating. Since it is from the 1930’s it is 110 volts DC! Mechanical relays still function perfectly and since the building is not heated, the enclosure containing the relays has a light-bulb that is constantly on to provide sufficient heat as to prevent moisture and corrosion. The bulb is the original one from when the observatory first began operation.
The David Dunlap Observatory is Canada’s largest optical telescope with a primary mirror measuring more than six feet (74″) in diameter. Because there is no coating to the mirrors in the telescope, they must remain covered when not in use. That requires a person (often Paul) to climb into the structure to take the covers off and place them back on. Because the entry path into the structure is small, jackets or sweaters must be removed in the dead of winter and crawling about in the ambient temperature – which is cold!
The property also includes an administration building with an impressive library meeting rooms and two smaller telescope domes. We were given a tour of that by Karen Mortifield, who manages Administration and Public Affairs.
We had some new members show up; Elizabeth Mathews from Owen Sound with her son Justin, Neil Johnston from Aurora, and Don Stoyles who happened upon us in the MacDonalds parking lot and decided to join the Club!
The drive to Belfountain followed a route George Dyke mapped out that involved taking King Vaughn Sideroad pretty much all the way from Bathurst Street to just east of Bolton. Fortunately the urban sprawl has not reached that far north (at least not yet) and it is still a lovely country road with little traffic. The group stopped for lunch in Bolton before continuing over to the Forks of the Credit river and taking a hilly and twisty route around that area.
The outing was a great way to kick-off the 2016 driving season for the Club, very heartening to see such a diverse representation of Citroëns and fun to mingle with everyone!
You can understand how the telescope at the David Dunlap Observatory works and its significance in this National Film Board of Canada presentation filmed in 1959 (released in 1960): David Dunlap Observatory, Universe (1960)
Also check out this tour given by Paul Mortfield to The Royal Astronomy Society of Canada (RASC) members on a very snowy February 2011 Saturday evening: https://www.youtube.com/watch?v=BYmC4ceRCQE
More info on astronomy can be found on Paul Mortfield’s website: https://www.BackyardAstronomer.com