October 2, 1942. Photo No. 20. This view of Staniford Road shows the method of mixing the Soil-Cement materials in place. The 22 inch Double Disc Harrow is being hauled by the heavy Allis-Chalmers Tractor while the Killifer Spring-Tooth Harrow is being hauled by the smaller Allis-Chalmers Tractor. The combination of these two harrows does a very satisfactory job in getting the aggregate thoroughly mixed. Work done by the Burlington Street Dept.