He adds that the full benefit of the impervious pavements as regards the cost of scavenging has not yet been felt, for almost all the lines of streets so paved are intersected at short distances by streets of ordinary jointed granite setts or macadam, whence a quantity of mud and refuse is dragged by the traffic on to the asphalted jointed roadways, which are consequently debited with the cost of removal of some effete material not intrinsically belonging to them. Mr. Till, the Borough Surveyor of Birmingham, from investigations he has made on this subject, says that for granite pavement 2 cart loads of mud have to be removed from every 1000 square yards of surface, one third of a load for wood pavement[167] and 4 loads three times a day (a total of 12 loads) for macadamised roadways. The ultimate disposal of the material removed from the surfaces of roadways especially when they are macadamised is a difficult matter, as, being chiefly composed of silicate, it is valueless as a manure. In small towns, except during abnormally muddy weather, it may be mixed with the house refuse and sold to farmers, or the road scrapings themselves may be used as an excellent sand, if thoroughly washed, to mix with lime or cement to form mortar for public works; excessive accumulations of mud, however, must be got rid of in the most economical and speedy manner possible, and this is effected either by filling up old disused quarries with it, or depositing it upon waste lands, or forming embankments for new roads, but in no case should it be used, as I have before stated, upon building sites; it is difficult and expensive to destroy it or partially convert it into other matters by fire, so that if these methods which I have enumerated are impracticable, the only other method left for the disposal of the sweepings or scrapings from the streets is to take them out to sea in hopper barges and sink them in deep water. The last question that arises on the subject of scavenging before we consider the disposal of snow, is whether the onus of cleansing private courts and alleys which are not repairable by the urban authority should be borne by them or not.