They are very difficult to find and are best seen with the aid of a high intensity LED torch but here and there on the main timber beams around the house can be seen an X bordered by two parallel lines. These are carpenter’s levelling marks. When the main beams had been sawed and shaped, probably in a timber yard or in the forest, they were ready to be jointed using a mortice and tenon joint. But how to make sure that the timbers and the joint was cut at right angles? They were placed on trestles and moved until they were above a right angle, already scribed on the floor. A plumb bob would have been used to check this angle. The joint could then be accurately cut and the timbers were ‘signed off’ by marking them with the sign IXI.
I have found eleven of these marks around the house. See how many you can find.