Passengers travelling to Europe from the United States by the British packets had the luxury of being able to write letters during the first part of their journey from Boston and then place them in the post when the vessel called at Halifax, Nova Scotia. Such letters from Nova Scotia to the United States had to be prepaid to the border, United States postage could be prepaid or left unpaid.

S.S. 'Cambria' out of Boston to Sowell, Massachusetts, via Halifax, Nova Scotia, 3rd September 1847.

'At Sea, Sept. 2. 1847
My Dearest Wife - We were detained by the fog in Boston Harbor, not five miles from you till 2 oclock this morning. This delay, as you may suppose was not a little trying, & the more so as you may suppose as we might have gotten outside of the Islands if the Boat had sailed promptly at 12 oclock. The delay of a single half an hour occasioned the further delay of twelve hours.'

A letter written on board 'Cambria' out of Boston on the 1st of September; the letter was posted at Halifax and travelled overland via St. Johns to be exchanged between St. Andrews, N.B. and Robbinston, Maine. Postage to the border, one shilling and a penny halfpenny Currency had to be prepaid. United States postage could be paid or unpaid - in this case charged at ten
cents (at which time the 'PAID' portion of the Halifax handstamp was deleted.}