Notes: "W. H. Harling made nothing but handmade slide rules, never switching to automated dividing engines. Under high magnification you can see that all the lines and tick marks were hand-scribed, and the numbers were hand-stamped, even on their celluloid-faced slide rules, like this one. This slide rule would be considered an improved Mannheim model, with the addition of a K scale. Only the S, L, and T scales on the back of the slide are labeled. Look closely and you can see that the inch ruler on the beveled upper edge is divided decimally, 10 divisions per inch. This is a characteristic thing for W. H. Harling slide rules. This slide rule must have been UK government property at some time as the Air Ministry has put their stamp on the back."
