Chap. VIII.

15 HIT A IN.

531

Draining and embanking are among the most important operations of tlie civil engineer;the salubrity of a city or of an extensive district depends in a great measure upon themanner in which its superfluous waters are conducted from the surface, and from thevarious strata beneath, and we shall find that the laws now in force do not sufficiently bearupon this subject, nor do they respond to the present wants and wishes of tlie population.When the first regulations were made with regard to sewers, the construction of our housesdiffered as much as did the habits of those who occupied them ; the legal enactments nowcomprise little more than what refers to the carrying off the water from the surface of thesoil, or forming banks to rivers for the purposes of guarding against their overflow. Anisland like Great Britain requires more than ordinary attention to remove the abundanceof moisture condensed upon the surface, and a knowledge of the falls of the several streams,brooks, and other supplies to the rivers which form the arteries of tlie whole system, is thefirst thing to he obtained. The rate of motion of water dependent on its fall into the sea,the nature of the soil it runs through, and the length of its course, all require to he studiedbefore any instructions can he given, or a comprehensive plan he arranged for effectuallydraining any district.

To lay down a map of the whole country, on which should be marked the height of everytown and village above the level of the sea, as well as the boundary of every basin drained,would be a great work, but the advantages derived from such a labour would more thancompensate for its cost; and if the natural drains, which are the rivers, were shown, withall their tributaries, a comprehensive system might he based upon tlie knowledge so ob-tained, and there would ho no difficulty in framing laws which would effectually conduceto the general salubrity, and essentially increase the interest both of the proprietors and thecultivators of the soil. Dugdale, in his History of Kmbanking, tells us that draining adistrict or a country lias a divine origin, “for in the beginning the waters were gatheredtogether, and the dry land appeared, and that after the deluge the waters were dried upfrom off the earth, and the face of the ground was dry.”

All nations seem to have regarded the subject of drainage as one of primary importance,and at a very early period we find it practised in England, hut it was principally confinedto surface drainage of marshy districts, not forming a part of one grand whole, which is leftfor tlie present generation to contrive and carry out.

When sewers are to he made in a city or town distant from the sea, it is requisite toascertain what will he the result when they unite with tlie river into which they are toempty, and how the bed of that river is likely to be changed in the course of time hv thesilting up of the mouth, or by the throwing up of other impediments to its free and naturaldischarge. To have the sewage of a town under the management of one set of commis-sioners, and the great trunk into which they are discharged under another, whose object,perhaps, is only to maintain the navigation open, or to construct and keep in repair thebanks which confine it, is not likely to work well for the inhabitants of the places sodrained.

This is rendered obvious upon examining the state of many of our large and populoustowns, situated at the mouths of rivers, which pour their waters into another still larger.The Thames , for instance, receives the Medway, the Darent. and others; and if we lookinto the condition of the towns on their banks, we shall find that in consequence of theelevation of the beds of these rivers, which at first formed a natural drainage, the whole ofthe buildings, as well as the surrounding, and once fertile, district, is too often in the midstof a mass of stagnant water and decomposing vegetable matter, producing periodicaldiseases among the inhabitants.

The streamlets or brooks, which fall into these natural drains, and which once affordedabundant supply of wholesome water, have also become the receptacles of all that is filthy,being converted into common sewers, from the surface of which arise exhalations highlyinjurious. Never was it more necessary that some comprehensive plan should be laiddown to remedy this increasing evil, and to establish some power which should preventfurther mischief and bring hack the whole to a healthy state of management. This couldbe readily done if the country were divided into districts, not according to hundreds orparishes, hut in reference to their natural position : the whole of the land drained by ariver of any importance should be under one controlling power ; the valley on each side ofthe Medway, for instance, or that watered by the Darent, after being accurately surveyed,could have such local laws established as would at once show the necessity of maintainingthem inviolable, and that any infringement would be injurious to the interests of all.

The various mills erected on the rivers have all assisted to destroy the effectual drainingof the lands on their hanks ; the outbreaks of the springs have in many instances beenpenned upon, by creating a head of water, and a whole village has by this means beenplaced in a morass, its soil, once loose and dry, becoming saturated with water ; this isparticularly tlie case on the banks of those rivers where mills and factories have been longestablished ; and we often find the sill, over which the supply to their water-wheels formerlyran, at a depth of 8 or 10 feet below its present level. Now, it must he evident, that had

M M 2