1835.] 



FARMERS' REGISTER. 



303 



rating the bottom. Nature teaches this when she 

 cracks these impermeable strata bj the heat of 

 the sun, and the water sinks in tl . Clay 



, .1 i the b ittoms if i .crack 



sometimes to th feet, or 



more; hence the thirsty nature created of these 

 soils, and tii ' hey drink through 



these throats. Where a body of low 

 generally oi this character, it requires doi 

 quantity of water in very dry w 

 a freshet, th ires drinking in the water as 



fast as it spr ' I .In this wa; . 



soils become very rich, 

 with, the sediment of the wa 

 ed and veiny ap| 



with the spade, it is throu res that 



so much rain water is collected under the low 

 grounds, in the permei ' im of sand 



the clay. For the water that falls near the old 

 channel, and the spring's about, th 

 answer as an outlet which 

 now of another margin ditch along the i 

 range of hills at the oilier border of the low 

 grounds. 



By a sort of comparative anatomy, the constant 

 circulation of water in the earth and atmosphere, 

 by the distribution of showers, and again draining 

 it oil" by streams, may be likened to the circula- 

 tion kept up in the human body b}- the heart, 

 veins, and arteries: in which the 

 the heart, the rivers the veins, which conduct the 

 water to it, and the clouds- the arteries, by which 

 alter a certain preparation, it is agai 

 over the surface, and through the body of the 

 earth. In this system, the main drain A £ C, 

 ma}- represent one of these li ins in the body 



of the low grounds (the Vena Cava, if you 

 choose — the largest vein in th 

 the minor aqueducts, its various ramifications. 

 The beauty oi this system is, that the 

 suddenly emptied ail at once into the'Fena 

 but by various avenues, gradually enlarging, as 

 the water accumulates. 



Thus I have endeavored to illustrate the theory 

 and practice of draining; ail the fundamental prin- 

 ciples of which, and their application, are embra- 

 ced in this figure, the most distinguishing feature 

 of which is, the main carrier of the stream A .E C. 



We will now proceed to point out ( lie manner 

 in which it acts, in the reduction of freshets. Re- 

 claiming of land, subject to inundation, from fresh- 

 ets, is -a branch of draining upon a large scale. 

 The principle is the same as in drawing off any 

 other superfluous water. The object of the re- 

 duction of freshets, is to prei of land 

 and the destruction of crops. The former i 

 by washing and disfiguring it, and the latter by 

 drowning the plant by soaking the roots, or by 

 destroying its structure, by caking the leaves with 

 mud, thus stopping up their vessels. To prevent 

 inundation, either of two things are nee 

 that is, either to clean out the old channel, and oc- 

 casionally straightening its bends, or changing en- 

 tirely the bed of the stream. In this in 

 the latter operation is exhibited. The currenl 

 here is taken out of a very crooked channel, and 

 made to run in one entirely new, and p< 

 straight. The reason why this channel prevents 

 the inundation of the land, will be the principal 

 subject of the remarks which follow. It is entire- 

 ly owing to the increased velocity, given to the 



current in it. This depends entirely on the form 



and construction of the channel. As soon as the 



current is introduc is channel, it becomes 



to all the laws w em the motion of 



idincondui id- open canals. Hence 



all that is known of these laws, may be here ap- 



ind hence too, the necessity to the drainer, 

 of a k of those sciences, hydrostatics, 



and hydraulics, (latterly dignified with the title of 

 hydrodynamics) which make these laws the sub- 

 their investigation: the first of which con- 

 cerns the equilibrium, weight, and pressure of flu- 

 ids — the latter, their motion. If a knowledge of 

 dynamics, (the action of forces on solid bodies re- 

 sulting in motion,) is useful to every one who 

 "owns a horse," in order to understand his speed 

 and tractive pow insighl into the 



above sciences, will be of no disadvantage to him 

 who owns a canal, to understand the effects of the 

 velocity of its current, and its power on the land, 

 t mainly to two laws, namely: 



ire, and the force of gravitation — whether 

 it is confined and at rest, (for it never is at rest un- 

 less it is confined,) or in motion. The first is that 

 force by which i s particles press on and against 

 each other, or on any solid body. This pressure 

 is equal in all directions, upwards, downwards, 

 and laterally, and is increased by the pressure or 

 weight of the atmosphere. Cj on tins principle 

 water spouts from the side of a vessel, when a hole 

 is male into it, and as often as this operation had 

 been performed, the property was first distinctly 

 stated by Pascal. The second is, that force which 

 draws bodies to the earth, or by which a lio-hler 

 body is drawn by a heavier: and although here, 

 as jn th ns of- apples had fallen 



to the earth in die sight of the vulgar, Newton 



■ id it, with a philosophic eye. But as 

 those two laws are resolvable into the same (for 

 what is the pressure of water, but its weight; and 

 what is its weiirht, but the force of gravitation 

 drawing it down?) all the phenomena of this fluid 

 may be said to be governed by the force of gravi- 

 ty. 



Let us see now, how the atoms of water are 

 put and kept in motion by these two laws, which 

 we shall consider as distinct, for the sake of clear- 

 ness. First, by the force of pressure. If the sides 

 of a vessel of water, sitting on a perfectly hori- 

 zontal level plane, be suddenly taken away, the 

 luid within will run off' in every direction on the 

 plane, even though it have not the slightest incli- 

 nation, ontinue f o run and spread until 

 diere is not one particle of water above the other, 

 • ii down when it. ceases. The pressure of 



i terthen is as its depth: and .therefore as 

 this diminishes, th" pressure diminishes, until the 



: ecomes so shallow and thin, that it ceases 

 to run. Hut its velocity is as its pressure; there- 

 fore its velocity is as i;s depth (when unconfined, 

 and in motion.) Therefore by increasing thedepth, 

 die fill (or inclination of the plane) remaining the 

 same, the velocity is increased. The reason of this 



re in water is this: the atoms or panicles of 

 water, are so mobile, round, and slippery, and the 

 cohesion of them so slight, that the upper parti- 

 cles pressing upon, the lower ones, push them to 

 one side: for the atoms of water are not like lead, 

 or any other compressible, substance, the particles 

 of which may be mashed together — but the infe- 

 rior atoms rather than yield to the superior by 



