Notes: "The Amsler Type 7 is essentially a very large Type 4, made of heavier gauge components. It is a somewhat specialized planimeter in that it is optimized for measuring very large areas. As you can see in the pictures, the tracing arm is 19 inches long! Although the tracing arm is adjustable, this planimeter would be very inconvenient for use on small areas. The serial number is 46478."
