Make None given but research by J Bready has revealed it to be an Omnes.
Model None given
This rule was cheaply made but has survived for around 80 years.
1. The slide is a most unusual one, being all metal (tin plate) with painted scales.
2. The cursor consists of a folded strip of plastic held in place by a metal clip.
3. The patent was issued in 1919, so the rule was probably made during the 1920s.
4. The rule has sin, tan and log scale on the reverse face. There is a small mark on the reverse stock for the log scale.
5. The rule is provided with two slides. The second one including scales for electrical calculations.
6. The only gauge mark is 1146 (Gunner's mark) suggesting an artillery use.
7. A copy of the original Patent Specification can be found here. (Thanks to Peter Hopp for obtaining the Patent and providing me with a copy.)
8. A copy of instructions in a contemporary book (Slide Rules and How to Use Them by Thos. Jackson) can be found here. (Thanks to Jim Bready for providing the scans of the spare slides and instructions.)
9. I have another US made Richardson rule which also is made of tin plate.

Front view
0005-metal01.jpg (29537 bytes)

Front left
Showing gauge point of 1146
0005-metal02.jpg (17789 bytes)

Plastic with metal clip
0005-metal03.jpg (16534 bytes)

Rear view showing trig and log scales
0005-metal04.jpg (23793 bytes)

Front and back - slide 1
0005-metal05.jpg (58646 bytes)

Front and back - slide 2
0005-metal06.jpg (53969 bytes)
Manufacturing date Patent is dated 1919
Length 10"
Material Metal with painted scales.
Scales A [R,C/S,L,T] D
The A scale is displaced by 0.89 (app)
Cursor Folded plastic with metal clip
Documentation None
Condition Very well used but all there