I recently acquired the book Souvenir Number of the Illustrated War News. History of Riel's Second Rebellion.
http://www.abebooks.com/servlet/BookDetailsPL?bi=2302496650&searchurl=sts%3Dt%26tn%3Dsouvenir%2Briel%2Brebellion%26x%3D0%26y%3D0
In it, there is an illustration of French's Scouts who helped capture three Indian scouts just prior to the Fish Creek engagement. The image shows French's Scouts wearing spiked pith helmets. When I get some free time, I'll scan and post the image.



