Show J FINDING WEAR OF HIGHWAYS instrument recently designed and made to determine wear of concrete and other roads Prep prepared axed by the united states department ot of agriculture every user of concrete and other I 1 improved highways high waya will be interested in an instrument which lias has recently been designed and made in the research division of tee bureau of bf public lic roads for measuring wear of concrete and other surfaced cW it Is anticipated that from readings made with this instrument a large amours amok of valuable data may be collected not only regarding concrete roads but also concerning brick macadam and other types of surfaces the instrument consists essentially of two bearing plates each 2 inches in diameter pivoted on uniform joints to a spanner 11 inches long in the mid point la Is mounted a micrometer plunger lunger i has a travel of I 1 inch and whose dial Is graduated to read 0 a or measures wear of roads one one thousandth of an inch in order to form a base to which measurements ure ments can be referred from year to year brass plugs are set in the pavement where readings are desired ReL healings dings are taken by resting the hearing bearing plates on the roads surface and allowing the plunger to rest on the base plate of the VL pg kg the instrument ment is plumbed with the aid of 0 a level and the spanner bar is held parallel to the center line aln of the road other readings may be taken with the bar at right angles to the center line of the road an important advantage of this in is that oat accurate data can be acquired rapidly abid without interrupting traffic the base plate 11 in the pavement Is protected between readings by covering co yering 0 it with cotton waste hil anil topping W with ith putty th the bras I 1 j plu plugs F g are readily set in any pavement t while it is being laid and at any future time by drilling holes with star sta r drills and setting the plug in cement grout |