Sliding rule and protractor

摘要: An extensible rule and protractor formed by an equally dimensioned pair of superposed strap members, having indicia thereon, secured together a screw projecting through one member sidably received longitudinal slot in the other member. Guide pins, on entering grooves member, maintain members alignment when is moved longitudinally relative to other. A circular groove intersecting at end portion slidably receive pins permitting angular rotation with respect measure define selected position.