Otis King Logarithmic Calculator Model 'L'. This is a logarithmic cylindrical pocket slide rule with helical scales to add subtract multiply and divide numbers, made in England by Carbic ltd., London in the early 1960s. The model L has a linear scale section on the top. A linear scale on a slide rule is used to find logs and anti-logs, which can be used along with multiplication and division to do arbitrary powers and roots. This slide rule is a type C, model L, with scales 429 and 430 and serial number v8205, It is in very good condition in an original box and comes with original 8 page instruction manual from the transit period between 171 Seymour Place, London, W1 and 54 Dundonald Rd, London, SW19