Quote:
This would have been internal mail (Upper Canada) for which a uniform rate of 3d currency per 1/2 oz irrespective of distance was in effect as of April 6, 1851 (Robson, p.106)
yes, there was a 3d rate beginning in 1851, but the letter was sent in 1850. The Canadian postage was 4½d currency for a distance under 60 miles for the rates by distance in effect in 1850.
I'm not sure what the manuscript marking in the upper left represents. It could be the number 31 which might be docketing by Kennedy indicating it was the 31st letter in that account and that it was sent paid or it might be the 31st letter in a stack of letters sent to the post office with a note that the letter should be sent paid. It could also be a notation that it was the third copy (3d) of a letter sent in triplicate, but I think it would be unusual to send a letter to New York in triplicate.