ft., or 235,905,678.7 gal., sufficient to cover 72311 acres to a depth of 1 ft.

The sub-humid region is the strip of country running north and south between the arid region, where irrigation is absolutely necessary to the successful prosecution of agriculture, and those portions of the United States in which the rainfall is usually sufficient for agricultural purposes. It includes portions of North Dakota, South Dakota, Nebraska, Kansas, and Texas, and may be described as a region where irrigation is not always necessary, but where agricultural operations cannot, with any assurance of success, be undertaken without it.

The average value of the irrigated land in farms in the United States was ascertained by the census of 1890 to be $83.28 per acre, and that of the non-irrigated land in farms $20.95 per acre.

The average annual value of the agricultural products of the irrigated land was ascertained to be $14.89 per acre irrigated, and that of those of the non-irrigated land $6.80 for each acre improved.

The average first cost of the irrigated land, including purchase money, water rights, etc., was ascertained to have been $8.15 per acre, and the average annual cost of the water supply $1.07 per acre.

The total value of the irrigated farms of the United States, as reported by the farmers themselves, was, in round figures, $296,850,000, an increase of $219,360,000, or 283 per cent, upon their cost, including land, water right, fences, and preparation for cultivation.

The total value of the productive irrigating systems was found to be $94,412,000, an increase of $64,801,000, or 219 per cent, upon their cost.

If the diameter be doubled, nearly 5.8 times the quantity can be passed

POWER REQUIRED TO RAISE WATER FROM DEEP WELLS BY PUMPING. (APPLEBY.)

APPROXIMATE COST OF DIFFERENT KINDS OF PIPE USED FOR IRRIGATION.

(WILCOX.)

AVERAGE COST PER MILE OF CONSTRUCTING IRRIGATING CANALS AND DITCHES.

CAPACITY OF CISTERNS AND TANKS,

in Gallons, for Each Twelve Inches in Depth.

Capacity of Cisterns in Barrels, Per Foot in Depth.

ROAD-MAKING. (Campbell.)

Drainage.-Perfect drainage, first of the foundation of the roadbed, secondly of the road surface, are the points in road-making on which too much stress cannot be laid.

The first is accomplished by underdrainage, tile drains being laid at a depth of three or more feet below the surface on each side of the roadbed at the foot of the grade and parallel to it. Care should be taken to fit and settle the tile in the trench so that, when refilling with earth, they will not be displaced. As a rule 2- to 4-in. tile will be sufficient. The joints should be close, and the grade a true line. Loose joints and an uneven grade allow silt to pass into the tile and remain there, destroying the drain.

Surface drainage is accomplished by open drains on each side of the grade, having sufficient capacity to drain, both the roadbed and the land adjoining. With open drains and with tile drains make and maintain a free outlet to the nearest watercourse. A drain without an outlet is useless.

Crowning the Road.-The graded portion of the road should be wide enough to accommodate the travel upon it, and not greater, the slope being uniform, not heaped in the centre. The crown should be well above the overflow of storm water, and should have a grade sufficient to shed water readily to the open ditches on either side. Do not round it up so as to make the grade steep and dangerous, under the mistaken impression that better drainage will thereby be secured. Nor should it be so low as to allow water to stand upon it in depressions. Under ordinary circumstances one inch or one inch and a half to the foot is