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DRAINAGE.

DEFINITIONS, AND SYNOPSIS OF THE DIVISIONS IN WHICH THE SUBJECT WILL BE TREATED IN

THIS WORK.

1. DRAINAGE is the collecting and conveying away refuse waters, and, other matters, from lands, towns, and buildings. It ascertains the means and methods of accomplishing these purposes in the most complete manner; and, as water is the principal agent in all cleansing processes, the means required for insuring its supply are among the necessary provisions of efficient drainage. By simply extending the same means, the supply of water may be made adequate to satisfy all other purposes; and it hence becomes desirable to include among the objects of drainage the entire supply of water for towns and buildings, and for the irrigation of lands. Sewers are among the essential means of town drainage, and therefore have to be so considered, and their positions, forms, sizes, and modes of construction duly ascertained. Our subject thus embraces several matters which may be treated separately, but which are properly branches of the art of draining, and cannot be consistently studied and usefully applied without a full appreciation of their several and intimate connections.

2. Beyond the limits of the subject of draining as

defined (1), it is also to be extended to the ultimate disposal of the refuse matters which it has first to remove from streets and dwellings, and one of its most important duties is to effect this disposal in such a manner that human health shall not be thereby impaired,and, moreover, that the matters removed shall be made available to the utmost in promoting the fertility of the land, and effecting all chemical purposes for which they are the best fitted.

3. The synopsis of the several heads under which we propose to arrange our facts, principles, and rules, is the following:

DRAINAGE.

DIVISION I.-DRAINAGE OF DISTRICTS AND LANDS. DIVISION II.-DRAINAGE OF TOWNS AND STREETS. DIVISION III.-DRAINAGE OF BUILDINGS AND DWELL

INGS.

DIVISION I.

SECTION I.-Sources of Water.-Natural and Artificial Supply.-Rain, Ocean, Rivers, Streams, Springs, &c.-Seasons, Evaporation, Temperature, &c.-Quantity required.-Nature of Soils and Crops, and position of Districts. Qualities of Water.-Rain Water, Sea Water, River, and other Waters.-Four kinds of Impurities. Modes of Purifying.-Subsidence.-Filtration.-Chemical Process.-Natural Filters.

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SECTION II.-Upper and Lower Districts.-Riverwatered and Sea-coast Districts.- Reclamation of Land. Modes of Draining, Pumping, &c.-Waterwheels, as applied for Draining and supplying Upland Districts.

SECTION III.-Means of conveying, distributing, and discharging Water.- Drains and Watercourses; Forms, Sizes, and Methods of Construction.-Implements employed.-Shallow and Deep Draining.-Stone, Tile, Earthenware, and Brick Drains, &c.

DIVISION II.

SECTION I.-Classification of Towns according to Position and Extent.-Varieties of Surface Levels and Inclinations.

SECTION II.-Supply of Water.-Public Filters and Reservoirs, &c.

SECTION III.-Width and Direction of Roads and Streets; Substructure and Surface.-Paving and Street Cleansing.

SECTION IV.-Main Sewers; Proportions and Dimensions, Inclinations, Forms, and Construction.Upper and Lower Connections.-Means of Access and Cleansing.-Adaptation for Street Cleansing, &c.

SECTION V.-Conveyance of Water.-Piping, Aqueducts, Reservoirs.-Pumping Apparatus, Steam Draining and Pumping, &c.

DIVISION III.

SECTION I.-Classification of Buildings.

SECTION II.-Supply of Water Levels.-Constant Service. Quantity required.-Cisterns.-Reservoirs.Filters.-Valves and Apparatus.-Piping, &c., &c.

SECTION III. Varieties of Manufactures, and best available Methods of Draining.-Arrangement of Separate and Collective Drains.-Proportion of Area of Drain to Cubic Contents of Dwelling-Houses.-Fall of Drains.-Mode of Construction.- Connection with Main or Collateral Sewers.-Means of Access, &c., &c.

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SECTION IV. Water-Closets; Arrangement and Construction.-Adaptation to various circumstances.Combined Arrangements for efficient House Drainage.Miscellaneous Apparatus and Contrivances. GENERAL SUMMARY AND CONCLUSION.

DIVISION I.

DRAINAGE OF DISTRICTS AND LANDS.

SECTION I.

Sources of Water.-Natural and Artificial Supply.—Rain, Ocean, Rivers, Streams, Springs, &c.-Seasons, Evaporation, Temperature, &c.Quantity required—Nature of Soils and Crops, and position of Districts.— Qualities of Water.-Rain Water, Sea Water, River, and other Waters. -Four Kinds of Impurities.-Modes of Purifying.-Subsidence.Filtration.-Chemical Process.-Natural Filters.

1. Water is indispensable to animal existence and health. The means of obtaining, treating, and economizing this vital liquid, are therefore among the most important objects of human art. The several sources, primary and secondary, of water, are the ocean, rivers, streams, lakes, subterranean collections or springs, and rain. Some or other of these sources are at our command, to some extent, in every region of the habitable globe. The applicability of the first-named four sources is limited by the geographical position of the district; the latter two of them are obtainable nearly everywhere. The ceaseless cycle of operations by which the waters on the earth and of the ocean mingle with the atmosphere by the medium of evaporation, and, descending in the forms of rain and dew, sprinkle the surface, and again unite through streams and rivers

in their common reservoir, is one of the most beautiful and interesting illustrations of the compensating principle of the economy of Providence.

2. In adopting the terms natural and artificial supply as contradistinguished, it may appear that the former should apply commonly to all the sources enumerated except the subterranean. We would, however, limit the term natural supply to rain and dew, since all the other sources require more or less of artificial means before they are generally available for the purposes of man. Thus the water of the ocean must undergo chemical change or distillation, and that of rivers requires artificial channels and conduits for its distribution. These, therefore, like the subterranean, for which wells and borings are necessary, have to be classed among the artificial sources of water.

3. The quantity of evaporation from land-surface is evidently more limited than that from water-surface, the one depending upon the retentive power of the super-soil, and the facility for capillary action, while the other arises from a source comparatively inexhaustible. The rate of the process is controlled by temperature, and accelerated in proportion to the heat acting upon the surface; the temperature being affected by the elevation, and reduced in proportion as the elevation increases. The joint result of these conditions is, that proximity to the sea, the river, or the lake, promotes the natural supply of water in the form of rain. The geography of the district, therefore, affects the facility or difficulty of the natural supply.

But another consideration also affects this supply, viz., the superficial features of the district. Thus a mountainous character, augmenting the surface exposed to oblique showers, increases the quantity received on

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