Fullerton 3715 Denmark Engine Divided Engineering Scale Triangular Ruler

This three sided ruler is a special engineering scale tool for creating and reading drawings at scale without complex calculations. It was first introduced in the 1930s. Older, high-quality rulers like this are ‘engine divided’, meaning a machine engraved the markings, ensuring high precision.
 
It includes a variety of engineer (or civil) scales on its six edges which correspond to the following dimensions, or parts per inch:
 
10 scale: 1 inch equals 10 feet.
20 scale: 1 inch equals 20 feet.
30 scale: 1 inch equals 30 feet.
40 scale: 1 inch equals 40 feet.
50 scale: 1 inch equals 50 feet.
60 scale: 1 inch equals 60 feet. 
 
These are used for large-scale projects like bridges, roads, and topographical maps, and are based on decimalized fractions of an inch. To use an engineer scale, you match the scale on your ruler to the scale of the blueprint. For example, if the blueprint's scale is 1" = 40', you use the "40" scale on the ruler, where each major increment represents 10 feet.
 
Ours is mostly clean with only Nancy's odd X mark on one end and some minor scratches.
 
H 15/16” x L 12 15/16” x D 15/16”
 
Disclaimer: We have tried to make sure colors shown in photos are representative of the real colors of each item. We have tried to identify all imperfections in descriptions, but we may have missed some. If you are unhappy with your purchase, let us know.