Otis King

Interesting cylindrical slide rules, made from the early 1920s to the 1960s. These ones are very early - they have serial numbers in the A range, and also have the white-on-black scales that only occur in some early models - all the later ones are black-on-cream. Both of them are in very good condition, and both came wih their leather carrying pouch. But that is only the beginning... see if you can spot the differences between them:

Otis King picture 1

Otis King  picture 2

Otis King  picture 3

Otis King  picture 4

Otis King  picture 5

Otis King  picture 6

The bottom calculator (Nr. A7303) is a relatively common (but early) Model L, with a black cursor. It has a 0-10 log scale on the bottom, with number 429, and scale 430 on the top, which consists of two parts, 1-10 log and 0-10 evenly divided.

The top calculator however (Nr. A8800), is rare as hens' teeth - not only has it hardly been used, it also has a nickeled cursor. That is not what makes it rare though. It is a different model, and not the model K that is also very common, but rather the model M, with scale nr. 441 on top (0.0025 to 100000 log - equivalent to scale nr. 418) and nr. 419 (1 to 10000 log) on the bottom. I have never seen another one like it. For the right price, and to the right collector, it may be for sale ...