Well, that made me take a closer look, and to look up some Canadian postal history. And that led some interesting places.
The stamp is correct for 1893, there are finer points to that whole series involving papers and colors to determine when and where it was printed, but While my wife collects Canada, I haven't really gotten into most of that.
The interesting bit is the rate described on the piece itself, Book post, printed matter only. That would be very unusual for a postcard, which went at the same 1c rate
From the 1893 Canadian postal rates
3rd Class Matter.—Addressed to Canada.—1. Transient newspapers and periodicals. Rate, 1 cent per 4 oz.; prepayment compulsory; limit of weight, 5 lbs. A single paper weighing not more than 1 oz. may pass for ˝ cent.
2. Book packets. Rate, 1 cent per 4 oz.; limit of weight, 5 lbs., except for a single book, in which case the limit is 7 lbs.
3. Miscellaneous matter. (a) Printed pamphlets, printed circulars, etc., and also seeds, cuttings, bulbs, etc.; rate, 1 cent per 4 oz. (b) Maps, lithographs, photographs, circulars produced by a multiplying process easy to recognize, deeds, mortgages, insurance policies, militia, school and municipal returns, printed stationery, etc.; rate, 1 cent per 2 oz.
Circulars, Prices Current, etc., to pass at 1 c. rate must be ENTIRELY PRINTED. Any insertion in ink is not permissible, except the name and address of the addressee, the name of the sender and the date of the circular itself.
So 1 cent was pretty much the minimum. (Regular newspapers were carried free to other cities!)
Here's an example of a different photographers wrapper for photographs from the same era.
It's possible that the piece is from either a brochure, or a similar wrapper, and happens to have part of the advertisement for that picture on the back.