Dating to the late 1940's, a nice example of an Otis King's model 'K' type B cylindrical slide rule calculator with black on white scales.

It carries the serial no P3620 on one cap, with 'Made in England' on the other and has very clean and legible helical scales enabling numerous mathematical calculations.

The patent no. is 183723 with scale 414 on the bottom and 423 on the top, with the dual screws holding the frame identifying it as a type B model.

In good condition, it was made by Carbic Limited London in the late 1940's, and retains all of its chrome plating, although there is some blistering of the black paint on the main barrel (see photos).

It's in good working order and comes in an original card box, along with the original 8 page instruction booklet, plus a later copy of a blue marketing leaflet.