This is a rather unique slide rule which Dr. Heinz Haury had made specially for use in his own chemical factory in Germany. It is for easy calculating a standard deviation for a “Haury-test” that must have been a much used specific test in this chemical factory to sport its name as well. Not sure who mad either, it is completely made of an early type of plastic and utilizes no cursor. The back of the slide is blank, so no hidden additional scales. It measures 33,5 cm or 13 1/2 inches. Do check the video below on how to work your vintage man tool : slide rule operation instructions!
