Hard to tell, but if that's an iron pontil mark, then it should be a bit older than 1866. Todd von Mechow lists two, both from Ontario, but neither are pontiled, and are blown in a plate mold. Yours appears to be an unlisted, and earlier variant. Might want to send him pictures. Great find!
This site offers a history of North American antique soda and beer bottles. Within you will be able to date your old soda and beer bottles based on shape, color, base style, lips, and closures.
www.sodasandbeers.com