Instead of a line, after the end stakes have been placed, a _boning rod_, as it is called, may be used thus: A staff is used, with a cross-piece at the top, and long enough, when resting on the proper bottom of the drain, to reach to the level of the marks on the stakes, three feet above the surface. Cross-pieces nailed to the stakes are the most conspicuous marks. A person stands at one stake sighting along to the other; a second person then holds the rod upright in the ditch, just touching the bottom, and carries it thus along. If, while it is moved along, its top is always in a line with the cross-bars on the end stakes, the fall is uniform; if it rise above, the bottom of the drain must be lowered; if it fall below, the bottom of the drain must be raised. This may be convenient enough for mere inspection of works, but it requires two persons besides the cutters, to finish the drain by this mode; whereas, with the lines and squares, any laborer can complete the work with exactness. Another mode of levelling, by means of a mammoth mason's level, with an improvement, was invented by Colonel Challoner, and published in the Journal of the Royal Agricultural Society. It may appear to some persons more simple than the span level. We give the cut and explanation. "I first ascertain what amount of fall I can obtain, from the head of every drain to my outfall. Suppose the length of the drain to be 96 yards, and I find I have a fall of two feet, that gives me a fall of a quarter of an inch in every yard. I take a common bricklayer's level 12 feet long, to the bottom of which I attach, with screws, a piece of wood the whole length, _one inch wider_ at one end than at the other, thereby throwing the level one inch out of the true horizontal line. When the drain has got to its proper depth at the outfall, I apply the broadest end of the level to the mouth; and when the plumb-bob indicates the level to be correct, the one-inch fall has been gained in the four yards, and so on. I keep testing the drain as it is dug, quite up to the head, when an unbroken, even, and continuous fall of two feet in the whole 96 yards has been obtained." [Illustration: Fig. 60.--CHALLONER'S LEVEL.] SPADES AND SHOVELS. [Illustration: Fig. 61, 62, 63.--DRAIN SPADES.] No peculiar tool is essential in opening that part of the drain which is more than a foot in width. Shovels and spades, of the forms usually found upon well-furnished farms, and adapted to its soil, will be found sufficient. A Boston agricultural house, a year or two since, sent out an order to London for a complete set of draining tools. In due season, they received, in compliance with their order, three spades of different width, like those represented in the cut.