Word: impact
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Dates: during 1900-1909
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...various stones. Fragments about the size of those used on roads are inclosed tightly in a diagonally pivoted iron cylinder which is rapidly rotated for five hours, the motion throwing the stones from one end of the cylinder to the other and subjecting them to both wear and impact. The relative toughness is determined on small fragments of the stones by subjecting them to constantly increasing blows from a spherical hammer until they split. The same machine with special appliances is used for testing the cementing value of stone. This is done by striking small quantities of pulverized rock lightly...