Thursday 25 August 2022

A Cooke in Canada and the North Star

 In 1892 Dr J C Donaldson of Fergus, Ontario who had been testing the excellence of his 3.5 inch Cooke by ascertaining the smallest aperture with which he can see certain well known doubles.

On the night of October 9th he was able to see the companion of Polaris with his glass stopped down to an aperture of 1.8 inches.

With the same aperture on the 12th December, he saw the companion of Rigel, and the 4 stars of theta Orion, 

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