Selective assembly: in the foreground the bore of bearings to be used on the main headstock spindle are checked: in the mid-ground the diameter of a spindle's trunnion surface is measured and in the background a row of spindles, complete with their bearings.

George Mills, a veteran employee with 48 years of service and long-time head of the Hendey laboratory, seen testing the pitch accuracy of a sample screw generated in a lathe. The laboratory was not only guardian of mechanical standards but also undertook metallurgical, chemical and physical analysis of all materials used in the company's products.

Use a Scleroscope (type D) to measure the hardness of a foundry-sample, gray-iron bar.
The Scleroscope was one of the first "non-marking" hardness-testing instruments and introduced circa 1905 by the Shore Instrument Mfg Company Ltd, of New York. It used a diamond tipped "hammer", held within a glass-fronted tube, that fell, from a height of 10 inches, onto a test specimen. The rebound of the hammer was measured on a graduated scale of "Shore" units each divided into 100 parts that, provide (in effect), a comparison with the rebound that might be expected from hardened high-carbon steel.
The hardness reading was really an expression of the material's elasticity and, as such, could be affected by the sample's mass, surface smoothness, depth and contour. Unlike many other methods of hardness testing a Scleroscope unit (in normal use) left only the slightest mark on the material under test. However, if further investigation was required the sample had to be turned so that the hammer fell on a new site; hitting the original impact point caused a higher bounce due to the slight work hardening from the first blow.
Two models were offered: the simple "C" with graduations to 140 that required the operator to estimate the rebound by eye and the more sophisticated Model "D"; this latter type was scaled to 120 and caused the hammer to strike a lever attached to a dial gage that saved the reading. The measurement symbol for a Scleroscope tester is "HS"