REPAIR OF CITY STREETS. 239 



These are the quantities as given by one authority, but from 

 a comparison with the amounts actually used during a period of 

 ten years on thirty-nine roads, having very various amounts of 

 travel upon them and being repaired with all kinds of road metal, 

 it would seem that the above figures are very ample. 



Repairs op Macadamized and much frequented Streets in 



Cities. 

 In this case, where the amount of travel in one day is often 

 greater than that of a month or more on the town road, the sys- 

 tem of continuous repairs ceases to be the best available, on ac- 

 count of the incessant throng of vehicles not giving any repaired 

 place a chance to become solid before it is again ploughed up 

 and scattered. Thus in the city of Paris on the Boulevards, &c., 

 the continuous system has been abandoned and the practice now 

 is to let the street gradually wear down three to four inches, then 

 close half of it (divided " fore and aft") to travel, loosen it all 

 up with picks and put on a layer three or four inches [best not 

 to put on more than that] spread a thin layer of sand over 

 this, sprinkle and roll heavily. It often happens that the men 

 put too much of the sand on ; in that case, the road, after it is all 

 done, is finally well watered and the roller again passed over it 

 a number of times. This operation causes the superfluous bind- 

 ing material to come to the surface in the shape of thin mud 

 and leaves the road covering as hard and smooth as mosaic, 

 making a most excellent drive-way. It emits a sonorous, ring- 

 ing sound on being driven over and remains clean and without 

 mud throughout the heaviest rain-storms. The rolling of the 

 streets in Paris, is done by a company owning a large number of 

 steam rollers ; in paying them for work done, the city was obliged 

 to go back to first principles for a measure of such work, it being 

 found impossible to estimate correctly by the square measure of 

 surface rolled to such and such a degree of hardness. The 

 measure adopted is that of weight multiplied into the distance 

 it has been moved, or " feet pounds " as we should say. It has 

 been found from many years experience that to roll one cubic 

 meter of macadam requires 4-5 " Kilometer-tonnes " and this 

 is true whether the layer of macadam be three and one-quarter 

 or ten inches thick. Expressed in our measures this is 11,020- 



