A. G. Thornton Comprehensive Master scale template
A. G. Thornton
Master template for drawing scales
Notes: "This is a steel template for the scales on drawing or measuring instruments. There are 8 scales on this template, each are a set number of divisions per inch or mm. The six scales for inches are divided into 211.2, 44, 41.6, 192, 200, and 240 divisions per inch. The mm scales are 6 and 10 divisions per mm. The template is not marked with a brand name, but a handwritten note in the box says ""A. G. Thornton"". The box is marked in three places, ""Comprehensive Master"". There are no logarithmic scales, so this was not used for creating slide rule scales. More likely it was for the scales on drafting rulers."