decided upon in working out the survey notes. In grading with water, the safest way is to go too shallow rather than too deep, as it is not always practicable to fill in with loose materials under the tiles in running water. This can, of course, be done by using gravel or coarse stones which will not be displaced by running water. Many practical ditchers require no survey whatever if there is water in the ditch, and ample fall, since they

Figure 94. Ten men performing successive operations in opening the ditch, grading the bottom and filling the ditch.

can lay out the general plan of a drain with the eye, and by carefully using the water as an indicator can make a thoroughly practical drain.

The triangular tile drain grader, shown in Figure 95, may be made any suitable length, as 10, 12 or 161⁄2 feet. When the lower board is level, a large nail is driven in its upper edge immediately under the point of the plumb bob. If it is a rod long, it may be adjusted to grading 2, 4, 6, 8, 10, 12, etc., inches per 100 feet by using blocks one-third of an inch thick under one end, driving a nail under the point of the plumb bob each time the upper end is raised by the addition of one of

these blocks, just as the device shown in Figure 96 is adjusted to similar changes in grade by moving the bolt supporting the upper board into holes one-third of an inch lower. If the device is shorter than 161⁄2 feet, the size of the blocks used in placing the nails should be proportionately thinner. Thus, if 10 feet long, the blocks should be one-fifth of an inch thick. Figure 96 illustrates a grading frame used in leveling ditches. A, spirit level; B, hinged end of board at back or lower end of frame; C, loose end of board at front of frame, which can be lowered or raised, so that, when the spirit level stands level, the bottom board, D to E, will have the desired slant to give the bottom of the ditch the proper grade. The frame is pulled forward as fast as the ditch is lowered sufficiently to allow of its being moved without throwing the spirit bulb out of level. A change

Figure 95. Triangular tile drain grader.

for a steeper grade is made by putting the pin at C in a lower hole, and to a slighter grade by putting the pin in a higher hole.

Grading devices.-In Figures 95, 96, 97 and 98 are shown different forms of leveling devices found useful in making the bottom of the tile drain at a uniform grade. Proceeding from one station to another, the accuracy of the grading frame is tested by measuring down from the stake at the new station. If the grade has been too great, and the ditch is not sufficiently deep, the grading frame should be readjusted to a slightly less grade, and if the ditch is too deep when the forward station is reached, the frame should be readjusted to a greater slant.

A small steel wire, such as is used in wrapping brooms,

stretched from station to station, 50, or even 100, or more, feet apart, and placed at a given distance above the desired grade, serves as a line from which to measure down to the bottom of the ditch. The ends of the wire can be placed at the same distance above the desired grade and parallel to it. The depth for the ditch at each point being known, the wire can be attached to each stake high enough to make the wire a given distance above the desired bottom of the ditch, say 7 feet. It will be convenient to have it high enough to be out of the way of throwing out the spadeful of earth. To find the proper depth to make the ditch, an L-shaped meas

uring rod may be used to measure down from the wire, which may be placed at one side. By using stakes, as in Figure 101, the wire can be stretched so tightly that it will not sag.

Laying tiles in the ditch.-Where the material in the bottom of the ditch is not too soft, laying by hand, as shown at I, Figure 94, is the better way of placing the tiles in position. When placed by hand the tiles can be so turned and adjusted that the ends will be sufficiently close together to prevent earth falling in between. Where material under the bottom of the ditch is so soft that treading on the tiles displaces them, it is necessary to

lay the tiles with the tile hook, as shown at K, Figure 94. By exercising a little dexterity, the tiles can be placed, and even revolved on the hook, so as to make the unions fairly tight. There is rarely danger of having the ends too close together, as a very narrow opening will allow the water to enter. As soon as the tiles are laid, they should be covered with a few inches of earth and tramped so that they will not

IN

2"

3"

4"

5"

Figure 97. Mason's level.

be displaced. If the earth forming the side of the ditch is not fine sand, or if it has sufficient clay in it to bind well, sufficient to pack about the tiles can be cut loose with the spade by the workman standing in the ditch and tramped firmly about the tiles.

Where the branches lead off from the line of the ditch, the the unions should be carefully made. Union tiles, as shown in

Figure 98. Shows the manner of marking the Figures 75 and 77,

are

upright of Figure 96 so that the holes may be
bored at the desired distance apart. A horizon-
tal line is drawn through the center of the hole
which supports the top board when it is par-
allel to the bottom board, and another at each pose.
inch further down for several inches. Then each

used for this pur

Where these are

inch is divided into three equal parts by lines not available, as in case

and three vertical lines are drawn an inch or

more apart. By boring a hole at each inter- of breakage or long dis

section, the holes are made at intervals of one

third of an inch apart, sufficient to give an added tance from factory, unions

rise in the grade of 2 inches per 100 feet, the bottom board being 161⁄2 feet long.

can be made by cutting

a hole with a cold chisel in a tile on the main line and fitting to this hole the end of a tile on the branch line.

Figure 99.

Students leveling bottom of tile ditch with device like that shown in Figure 96.