1765 Scottish Bishop's Mark

The Bishop Mark was an early form of date cancellation used to 'prove' that the mails were being properly and timely handled by the British Post Office. Numerous complaints regarding 'delays' had been received, such that theofficials thought iut necessary to mark the letters in a form that would indicate correct and speedy transit.
This letter is apparently from a solicitor in Edinburgh to a client in Argus regarding an action involving the recipient. Part of the advice is that; if the client has not already strated aplanned journey, he should alter those plans to attend the hearing slated for January 1766.
The Scottish Post Office used a split Bishop's Mark to enable placing dates and months together more economically than having a separate mark for each date! Later a double ring vs. single ring denoted the time of day the letter was posted.