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<p>The usual types of permeameter do not permit the use of higher fields than about 300 c.g.s., whilst methods for high fields commonly require the use of small specimens. In view of these facts, a method has been developed for testing long straight bars in intense fields. The rod is passed axially through the flat pole-pieces of a Du Bois electromagnetwith an air-gap of 2 cm. Surrounding the rod in the air-gap are three short coaxial coils of fine wire which can be connected to a ballistic galvanometer of variable sensitivity; these are employed to measure B and H. The method does not appear to give good results for H/sub c/. Results are given for tests on twelve rods, 6 mm. in diam. and 35 cm. long, of Norway iron, Bessemer steel, and tool steel res
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