B68-478 CIRCULAR SLIDE RULE. Webb's Stadia. Invented by civil engineer William Loring Webb and manufactured by Keuffel & Esser from 1903 through 1923, it was used in topographical surveying to determine the elevation and geographical position of points and objects. It consists of a wooden cylinder covered with paper scales, wooden handles at the ends of the cylinder, and a metal sleeve lined with felt. The sleeve, which is painted maroon with gold highlighting, holds the cylinder. There are a few spots in which the maroon paint has worn off, but otherwise like new. From the collection of Chuck Morgan. Fine 300-600