Road Materials.

The work of investigating and testing road materials which is now being carried on in the engineering laboratory of the Lawrence Scientific School under the direction of Mr. S. W. Page is of a very interesting character. The three principal tests so far developed are upon the resistance to wear, relative toughness and cementing value of 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 with a hammer until their cohesive power is destroyed. The machine makes a record of the energy and effect of each blow, as well as the final breaking point of the stone. The laboratory is the first of its kind in this country.