LECTURES AND ESSAYS READ AT INSTITUTES. 



281 



Curbing Box. Fig. 9. 



rather thick to sink in the sand, but it could, doubtless, be successfully used. 

 Fig. 9 is a view of a box, built after a design of my own of 1-16 boiler 

 plate iron ; its length is five feet; depth, 15 inches; width, one foot. Two 

 handles, B B, are put on for the purpose of moving; an edge of angle-iron is 

 riveted on the top. This was made for laying eight-inch tile. For smaller 

 tile, the pieces might be much nearer together. The back handle, B, is made of 

 three-quarter inch round iron to prevent the collapse of the back end, owing 

 to pressure from the sand. The arrangement has worked well. 



KIXD OF UNDER-DEAINS. 



Under-draius are best constructed of tile, and the shape best suited for every 

 place is the plain cylindrical form. The tile are now usually laid with 



the ends abutting against each other, 

 leaving as smooth a channel as possible 

 for the water. In soil that is not easily 

 washed, no protection at the joints is 

 needed ; in sandy or peaty soils the tops 

 should be covered, so that the water will 

 be forced to enter at the bottom of the 

 joint ; it will then be likely to be free 

 from sediment. The best covering for 

 joints of tile is, in my opinion, a piece of 

 closely mown turf, laid grass down. This is especially good, as ic seems also 

 to prevent lateral displacement of the tile. Small pieces of tarred paper, 

 of old tiles, of tin, etc., answer a good purpose. Tarred paper is always 

 cheap and convenient to use. Turf is sometimes objected to because of the 

 silt that may be worked into the tile. Tiie water gets into the tile principally 

 at the joints, though the tile is in itself porous. This was strongly illustrated 

 by a construction that was carried out by the Lansing Wheelbarrow Works, 

 owing to a misunderstanding of some of my directions. In laying the tile the 

 joints were completely enveloped with tarred paper. The result was that no 

 water entered the tile, and the paper had to be removed before the tile would 

 work. 



TILE LAYING TO GRADE. 



As already noticed in a previous place, this requires much care. It is usually 

 necessary to test the bottom of the ditch in advance of laying the tile. And 

 also every tile after it is laid. As this work will be a permanent job, if done 

 well, no pains should be spared in laying the tile, which is the least laborious 

 part of the work. 



My method is — and this method has only to be tried to be adopted by all — 

 to stretch a strong cord about three feet above the ground, and get this 

 parallel to the required grade, as shown in Fig. 10. Now by supporting this 

 string at intervals of 30 feet (see Fig. 10), the variation from a straight line will 

 be insignificant, and by measuring down the required distance one can determine 

 the correct bottom of the ditch with exceeding accuracy and with great celerity. 

 This method of preserving a true line for the tile I wish to call particular 

 attention to; for it may be used not only to preserve the grade line, but to 

 secure it, and hence be a substitute for a line of levels. Fig. 10 shows, I 

 think, quite clearly how the string is carried, the stakes or posts are driven 

 on opposite sides of the ditch, and then connected with a cross-bar. This 

 cross-bar should be arranged so that either end can be raised so as to be made 

 truly level. For this purpose tiiree forms of clamps are shown in detail at A, 



