Signedon top panel: LEEDS & NORTHRUP CO. / PHILADELPHIA / 256290 / MADE IN U.S.A.
mounted plaque: PATENTED / LEEDS & NORTHRUP CO. / PHILADELPHIA / SER. NO. / MADE IN U.S.A.
FunctionSuch an instrument is used to measure the resistance of electric conductors. For a short general description and other images, go to the following website.
This one is more recent but works on the same principle. The decade name comes from the fact that the resistance is measured in single units divided in four dials, each a multiple of 10, from 1 to 9999 Ohms.
Primary SourcesLeeds & Northrup, Electrical Resistance Measurements Catalog 40, 1927 [picture on p.10 matches instrument exactly]
Leeds & Northrup, D-C Resistance Measurements Catalog E-53, p. 26.
ProvenanceFrom the Department of Geology and Geography, Hoffman Laboratory, Harvard University, 1984.