Satellite Transits of Jupiter seen with a Cooke in Canada

 On December 12^th 1891 Dr Donaldson of Fergus, Ontario , who had a clear sky, Wrote:- 

“On coming back to the telescope (a 3.5 inch refractor by Cooke), about 6.35, I fancy, I saw that IV had emerged from Transit, and I could not help noticing, the great contrast in colour between it and III and Jupiter itself, being of a dark – bluish colour, apparently so dark in fact that when I tried my 2.25 inch glass upon it I could scarcely detect it at all. In the 3,25 inch, the sight was very interesting, the two satellites looking almost like a close double star of complementary colours, III being of a golden yellow and IV of a dark blue colour.