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HANDY-BOOK OF IIUSBANDRT. 



7T 



The line of sight taken across the tops of two of these boning-rods 

 will be exactly seven feet above the line of the bottom of the 

 drain, and a "plumb-rod" (which is a boning-rod with 

 a line and plummet by which to place it perpendicu- 

 larly) will have its cross-head exactly in a line with 

 those of the boning-rods, when its foot stands on the 

 true line of the bottom of the drain. The ditch may 

 be dug with the narrow spade to within 

 about two inches of the desired depth, and 

 it may then be trimmed to the exact line 

 (with the aid of the plumb-rod) by a finish- 

 ing scoop, Fig. 36. The position of the 

 laborer in the narrow ditch, and the mode 

 of using the scoop, are shown in Fig, 37. 



As the laying of the tile should be com- 

 menced at the extreme upper ends of all 

 drains, so that no dirt may be washed into 

 them ; and, as the finishing of the bottom 

 should^ immediately precede the laying of 

 the tile, lest its bottom be made uneven by 

 water flowing over it, the ditches should be 

 first roughly finished to the outlet, (at a little 

 less than the final depth,) for the removal 

 y of the water during the work, and the 

 Fig. 36.— Finish- Fig. 35.— Bon- boning-rods should first be set zt the upper 

 ing scoop. ingRod. ^^j^^ When the rate of fall does not 



change, the boning-rods may be set at intervals of from 80 to 120 

 feet, as the sighting may be accurately done at this distance. Of 

 course, a rod must be set at each point at which the fall changes. 

 The manner of sighting over the boning-rods, and the inter- 

 mediate plumb-rod, is shown in Fig. 38. 



If, by mistake, the bottom is dug out too deeply, the earth 

 with which it is filled up to the proper grade must be beaten 

 solid. 



Tiles — Kinds and Sizes. — There are various forms of tiles 

 in use in this country — known as " round," " sole," " horse- 



