One of our members has recently acquired a rule by W. F. Stanley of a type that we have never seen before.
The rule is 6" long, 2 1/8" wide overall and ¼” thick. The sliding section is ¾" wide, the other two arms of equal width. It is marked STANLEY LONDON; MARKS PATENT and, separately, 1885
The upper arm is bevelled which would suggest that it is used for drawing. It is marked in inches on the bevelled edge. On the top arm it is surface marked in lines of inches divided 2:1; 1:2; 1:4 and 1:8
On the sliding arm there is a line that would enable it to be moved a set amount of offset against the scales.
It is possible to work out how the rule could be used but we cannot think of a situation when you would need this.
Needless to say it is not in any of the Stanley or other drawing instruments catalogues.
Any thoughts gratefully received.