Virtual Museum > The early ones > slide rules
Mechanical Pencil
OK, I must admit that this one is a mystery to me. It looks like an adding machine, when you turn the head of the pen. However the scale is up to 36, and the circular scale on the head does not make too much sense (to me) either. Because of the 36, I think it could be related to Imperial measures, such as inches, feet or similar.
If you have any input on this one, feedbacks are welcome !!
If you have any input on this one, feedbacks are welcome !!
