Ashcroft Paper Tester

The Ashcroft Paper Tester was introduced in 1912. I’ve found advertisements and references to the tester up till 1920, but it would have been available for a longer time. A patent was applied for on July 5, 1912 and patent number 1048488 was granted December 31, 1912. The tester pictured above is marked on the dial "PAT. DEC.31,1912" which means it was made in 1913 or after. However, I have seen models that show "PAT. APPD. FOR" which means that Ashcroft Manufacturing started making these in 1912.

A more in-depth write-up about the Ashcroft Paper Tester can be found at americanstationer.wordpress.com