letter scale

This funny little scale doesn't have a logo or a mark. However, I have recently been able to find the name of the maker, it is the firm K & O Co. in full Kronheimer & Oldenbusch Company, located at 366-388 Butler Street, Brooklyn, New York, U.S.A. The first advertisement I found with an image of this letter scale dates from 1911. It was still advertised in 1912 and 1913. In 1918 the name Kronheimer & Oldenbusch was completely replaced by K & Oh Co.. The maker did know how to fold and forge metals. The tube parts of the standard and of the support for the plate are also made by folding. The standard and the round plate are fastened by soldering. The chart of 4 ounces is subdivided into parts of 1/8 oz. The scale is brass coloured and is not magnetic. I don't know if it is real brass or not. The ball shaped counterweight is almost completely filled. There is no leveling screw to adjust the scale to zero in case of a position on a slanting surface. I've seen the following variations of this scale: an egg scale, where the flat plate is replaced by a little cup to hold the egg; and a more fancy model of the letter scale, where the a little bit more heightened base contains a real stamp box, see this letter scale. There are also copies that have the K & O Co. logo on the bottom of the base.
Below some more pictures of this letter scale.