1857 thick soft paper 6d. reddish purple pair cancelled by 4-ring "51" on 1858 (30 Dec.) envelope registered from Brockville to Chicago, showing despatch c.d.s., straight-line
"registered" and "paid 3
d" handstamps in orange with, on reverse, Windsor and arrival datestamps. The only recorded multiple of the rare 6d., and the only multiple rate registered cover to the U.S. with 3d. registration fee paid in cash
