WATER PIPES 111 



The neat lines for retaining walls are obtained by 

 setting " A-frames " in position by the help of a transit 

 so that the neat line on top of the footing and the neat 

 line under the coping can be located by stretching strings 

 from frame to frame or else from a frame to the finished 

 wall. 



In order to secure a perfectly straight coping, especially 

 in long walls along city streets, it is suggested that a tran- 

 sit line be established on top of the wall before the coping 

 is placed, say 2 niches back from the neat line. This line 

 can be marked by crow-feet every 25 feet. 



Retaining walls at the foot of a slope are separated from 

 it by a swale gutter. The coping is so designed as to throw 

 the water falling on it backward into the gutter, where it is 

 collected by catch-basins or inlets. 



The matter of pointing is very important. The joints 

 should be thoroughly raked to a depth of at least 1J inches 

 before the pointing mortar is applied. Depressed joints 

 pressed in with a pointer's tool are much superior in dura- 

 bility to raised joints. Only the best Portland cement 

 should be used for this purpose. 



WATER PIPES 



The practice of laying park water pipes prior to the 

 completion of the grading work has sometimes been re- 

 sorted to. It has been claimed that this is advantageous 

 in lands to be filled and no doubt it is from the contractor's 

 standpoint, as considerable digging is thereby avoided. 

 The practice, however, is open to serious objection, as in 

 some places the pipes are almost if not entirely uncovered 

 and the driving over them of wheel-scrapers, dump wagons, 

 etc., frequently seriously damages the pipe. Furthermore 

 if the filling operations are not completed before winter, 



