Toronto Magnetic and Meteorological Observatory

The Toronto Magnetic and Meteorological Observatory is a historical observatory located on the grounds of the University of Toronto, in Toronto, Ontario, Canada. The original building was constructed in 1840 as part of a worldwide research project run by Edward Sabine to determine the cause of fluctuations in magnetic declination. Measurements from the Toronto site demonstrated that sunspots were responsible for this effect on Earth's magnetic field. When this project concluded in 1853, the observatory was greatly expanded by the Canadian government and served as the country's primary meteorological station and official timekeeper for over fifty years. The observatory is considered the birthplace of Canadian astronomy.

Compasses tended to "wander" from north when measurements were taken at different locations or even at a single location over a period of time. The astronomer Edmund Halley noted this and the problems it would cause for navigation in 1701. It was also believed that whatever was causing this effect might be causing changes in the weather, and that studying magnetic variations might lead to better weather prediction.

In 1833 the British Association for the Advancement of Science commissioned a series of magnetic measurements across the United Kingdom. Under the direction of Major Edward Sabine of the Royal Artillery, a multi-year measuring project began, with the results to be published in 1838. As the measurements were being made a number of proposals were put forth to expand the program worldwide. In 1836 the German explorer and naturalist Alexander von Humboldt wrote to Prince Augustus Frederick, Duke of Sussex, then President of the Royal Society, stating that a formal program was important to a nation with dominions spread across the globe. At the seventh meeting of the British Association in Liverpool in 1837, Sabine declared that "the magnetism of the earth cannot be counted less than one of the most important branches of the physical history of the planet we inhabit" and mapping its variations would be "regarded by our contemporaries and by posterity as a fitting enterprise of a maritime people; and a worthy achievement of a nation which has ever sought to rank foremost in every arduous undertaking".

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