Ames Lettering Guide
"This clear plastic metric lettering guide consists of a frame holding a disc with columns of holes and spacing settings.
The guide is designed to slide back and forth on a straight edge to create parallel lines. The disc is rotated to the desired spacing for guide lines by aligning the space setting with the height setting mark at the bottom of the frame. The sides of the guide are used for drawing vertical and inclined lines.It is used to put precisely-spaced lines on a drawing to assist with lettering. This guide was manufactured by Alvin and Company."—https://americanhistory.si.edu/collections/search/object/nmah_1836854
