While I'm at it here's another odd one, seems like a lot going on here, lots of cancels. Not sure which way is right side up. All comments welcome? I have lots more but will stop pestering everyone after this one.
I find this cover rather enlightening, That smudgy cancel has been evident on a lot of my Canadian stamps, and I always assumed they were perhaps cancels from Bank Cheques etc ie fiscal use. To see them on cover like this is great. It still intrigues me how they were applied...felt tip of some sort ?.. rubber canceller in decline?
I'd suggest a Registered cover, the two numbers, (405, 662) the book audit numbers, from each destination it passed, tied to the Postmarks.
I believe one is Toronto and Montreal Grand Trunk Railway, while the other I think is Trenton and Maynooth Railway Post Office. I'd have to research where change of trains happened, looks like Marmora on the map I found, I am no expert in RPO cancels though.