We try to limit our spending on anniversary gifts – but also to find something which the other will enjoy. When I found this little item in a CS recently, I knew it was just the sort of quirky gizmo which Bob would have fun with. It came in a neat wooden presentation case. I was intrigued, and after much discussion with James [the helpful assistant in the Trussell Trust Shop] and the pair of us squinting through the sights and wiggling the little lever, I handed over my dosh, and then came home to research it further.
It is a circumferentor, or surveyor's compass – that is, an instrument used in surveying to measure horizontal angles. Although it was superseded by the theodolite in the early 19th century, ‘Stanley’ of London continued to make them.
According to the instructions, “Practice with this compass will help a person develop the ability to visualize lines and planes in three-dimensional space. On the cover of this compass there is a Natural Sine Scale for calculations of different readings during a survey.
Under the cover is a mirror used for taking reflecting readings from the dial. The compass is composed of a magnetic needle that is balanced on a pin so that the needle can rotate easily and becomes aligned with the magnetic field lines at the location of measurement.”
“The ability to visualize lines and planes in three-dimensional space” does remind me rather of the phrase Time And Relative Dimension In Space. Well, WHO would have thought it? [next anniversary, should I get Bob a sonic screwdriver and knit him a long scarf?]