From Wiki

Bruning 2401

• Type: Closed Body Enhanced Mannheim
• Size: 5 Inches
• Material: Plastic
• Scales:
  • Front: A [ B CI C ] D K
  • Back: [ S L T ]
• HvH: 5777

Has a different-looking runner. Sewn leather case (pocket clip missing), instruction pamphlet, box. Inch and centimeter scales. Sines from the S scale are read on the B scale, tangents are read on C over the D right index. Tangents can only be read directly to 45 degrees. Results from L are read on D.

I paid too much for this at an antique store in Seattle. The box is original but the covering sleeve is splitting at the corners, because it was incorrectly repackaged at some time. (Impressive the original owner kept it. Shows an organized mind.) The case is in good shape (other than the missing pocket clip), is tan leather with the Bruning logo pressed in.

There is an instruction manual, 16 pages, 5.5x8 inches, on flimsy paper (like found in bibles, but less crinkly. It is folded to fit in the box; this was likely the packing problem i noted. The manual is copyright 1944, and notes "Indicator Patent Applied For" on the cover. The manual was written specifically for this model of rule, as opposed to a class of rules.

The runner does look different than the typical windowframe design, but I'm unsure what makes it novel enough for its own patent.

The original owner seems to be a G. Miller, of Bakersfield, California, An employee if the "Dept. of Ag., B of SPI" which turns out to be the California Department of Agriculture, Bureau of Shipping Point Inspection, which is now part of the Division of Inspection Services.

There are two addresses scratched into the reverse of the rule, neither of which are the location of the current Bakersfield SPI office.

When I got it, the rule had some light-colored dirt in the slide. I'd guess that Mr. Miller was an agricultural inspector with the occasional need of a quick calculation. I'm going to guess that he wasn't keen on keeping the rule in his pocket, but rather kept it in a desk or briefcase, and removed the clip as an annoyance.