[419] SCIENTIFIC MANUAL. 133 



The spades and scoops explain themselves. 



After the ditch is prepared for the reception of the tile, 

 the operator, standing upon the bank, inserts the arm of 

 the tile layer into the pipe, lowers it, and adjusts it to its 

 place. 



The gauge is used to secure uniformity in the width and 

 depth of the drain. 



The span-level is used to determine the exact fall of the 

 drain. It is useful to ascertain the amount of fall the 

 topography of the ground will afford, the proper location 

 of the drains, and the uniformity of the fall in the bottom 

 of the drain, while being dug. 



Klippart, in his "Land Drainage," page 393, thus de- 

 scribes this useful instrument : 



"Three narrow strips of board are required, each about 

 six feet in length ; these are nailed together in the form of 

 the letter A, the span or stretch being exactly half a rod. 

 From a nail or pin at the top, a plummet is suspended. It 

 is then placed, for the purpose of marking, upon a floor or 

 piece of timber, which is perfectly level, and the place 

 where the plumb-line touches the cross-bar marked. One 

 foot is then raised one-fourth of an inch, and the place where 

 the line crosses the bar again marked, and will show a rise 

 or fall of one-half inch to the rod. The foot is then raised 

 to half an inch and the bar marked, indicating one inch to 

 the rod. These markings can be made to any extent de- 

 sired, and the instrument, by dropping it into the drain 

 occasionally, will show that the drain is dug with uniform 

 fall, and precisely that determined on at the outset." 



This is a simple and cheap instrument, which will be 

 found useful on the farm for other purposes than that of 

 drainage. 



Clay suitable for drain tile may be found in every section 

 of Georgia where fine brick can be made. It should be free 

 from pebbles, and not too poor in clay. A small amount 



