
Here is another interesting registered letter, originating in Cincinnati on 1/27/1859.
This one is after the official US registry system was put into place (1855).
The letter is to Britain and the registry agreement at this time between the US and Britain was that the entire registry rate of 5c would be collected in cash (cash, at least in the US) by the country of origin (US here), and the other country would be credited with half (2 1/2 cents).
The rate to the UK at this time was 24c, and this was overweight, and necessitated a 4-times rate. So 4-times 24c, or 96c via a block of 8 12c #36's were applied to pay this.
This was carried on the British Cunard line steamer Europa, which left NYC on Feb 2, 1859 and arrived Liverpool on Feb 14.
Since this was carried by British packet, Britain was entitled to 16c per rate for the steamer, and 3c for internal British transit, equalling 19c. So 19c times 4 equals a 76c credit to Britain.
So why, then, is the credit, applied in New York City equal to 78 1/2 cents ?
Recall that Britain was entitled to 1/2 of the registry fee, so they got an additional 2 1/2 cents. That's why.
Note that the credit is in pen, and not via the typical New York red exchange handstamp with a number for the credit. That's because they didn't have a 78 1/2 cent handstamp.

To go along with this, note that the red New York CDS - just says PAID. It doesn't have the numeral credit in there. That was done in pen.
Another fascinating thing about this cover - in the US, the USPO made it clear that for registered letters, there were to be no markings on the cover which clearly identified it as a registered letter. In other words there should be no markings such as: "Registered", "Valuable", "Money", etc ...
If you look closely, there aren't any such markings from the US.
Britain, however, clearly didn't have such restrictions. There is a "REGISTERED" oval applied in London, and the nice Crown Registered as well.
For the US side of things the only clues to this letter being registered are:
- the 2 1/2 cent credit the UK
- the '2714' registry number applied in the lower right hand corner in NYC.
New York City used 4-digit registry numbers on foreign mail, and typically applied them in the lower right hand corner of such mail. Its a signature that is often found and is the most common way to tell registered foreign mail out of New York.