Page:On the Application of Sewage in Agriculture.djvu/6

, and an infinite convenience to the public. The manure obtained from them will be equal to the best guano, without having a more disagreeable odour, and the price obtained for it ought to leave a large margin for profit. There is only one principle which would appear necessary to insist on, in order to place the art of tillage on a sound foundation, viz., that the elements abstracted from the soil by the growth of corn and green crops, and the raising of cattle, must be restored to it in the shape of manure. And common sense must, therefore, tell us that "the effect of individual manures must be judged of by the condition in which they leave the field." At present the large proprietor sends his grain and flesh for sale to the great centuries of consumption, and accordingly loses the conditions for their reproduction. This is the natural cause of the impoverishment of lands by cultivation. There is no other; and this will sufficiently account for the present condition of those countries whose wealth was devoured by the great metropolis of the ancient world, and the future condition of many, by which our great cities are now supplied, and whose sewers cast into the ocean a species of wealth which neither art nor science can restore when once suffered to run to waste.