Make Carbic (Otis King), London, England
Model Model L, Serial number R1942
Model K, Serial number W7400
1. The spiral scales gave the equivalent of a slide rule 66" long.
2. There are two different models. Model K (the upper image) has two scales for multiplication and division, which reduces the amount of manipulation required during calculations. Model L (the lower image) replaces one of these with a scale of logarithms, which extends the functionality of the rule.
3. A copy of the instructions, covering both models, can be found here.
4. Dick Lyon has a web site devoted to Otis King rules and is always pleased collect information from owners and give advice.

Model K
0003-otisking01.jpg (19960 bytes)

Model L
0003-otisking03.jpg (26132 bytes)

Close-up - Model K
0003-otisking02.jpg (28894 bytes)

Close-up - Model L
0003-otisking04.jpg (50274 bytes)

Manufacturing date Model K, mid 1960s (email from Dick Lyon)
Model L, 1955 (pencilled note inside of box)
Length Cylindrical
Material Chrome and black metallic.
Scales Two spiral scales the equivalent of C and D and one the equivalent of L.
Gauge points None
Hair lines  
Documentation Original documentation came with one of the rules.
Condition Both very good with original cardboard box..