PLATE LXVI 
Fig. i.—Photograph of details of instrument for measuring wear of roads: A , Heavy 
mortar block; B, light mortar block; C, steel rod; D, level adjusting screws; E, 
adjusting rack; F, inside micrometer; G, steel bearing block; H, electric buzzer. 
Fig. 2.—Instrument in use on concrete road. 
