Overflow

“ The overflow will be continued and upward until the resultant is overcome by friction. The lengthening of the channel of overflow, as in the spring at Alvarado, furnishes a corroborating instance of how this law of overflow operates. The spring was originally on the level of the shore until the sand drifted by degrees and formed a ridge twenty feet high, but the water appeared at the top of the ridge. ”

“ I feel as if I were nearer to the vitals of the globe, for this sandy overflow is something such a foliaceous mass as the vitals of the animal body. ”

“ All the earth and air
With thy voice is loud,
As when night is bare,
From one lonely cloud
The moon rains out her beams, and heaven is overflow'd.
What thou art we know not;
What is most like thee? ”

“ But the people know when the overflow is coming and they are glad for it to come, so they put banks around some of it so that it is stored up for watering the land during the rest of the year when there is no rain. ”

“ An overflow results only when the surface that supplies the water-bearing stratum is at an elevation superior to the surface of the ground where the well is located, and the water-bearing stratum is confined between impervious strata. ”

“ From the latter circumstance, one would be led to infer that these flats are subject to overflow, and no doubt can exist as to the fact of their being, at least partially, if not wholly, under water at times. ”

“ The intensity of the centrifugal force will increase with the distance from the center of the earth, while gravity will decrease; the resultant will also increase. Thus, we find the strongest and most abundant overflows at the tops of mountains or on high plateaus. But suppose it had been fully proved that a particular overflowing spring was caused by hydrostatic pressure, it would still remain to be accounted for how the water got to that higher point. ”

“ See, how the stream has overflowed
Its banks, and o'er the meadow road
Is spreading far and wide! ”

“ In seeking the answer it will be useful to ask ourselves another question. What should we have expected the drop to do? Well, to this I suppose most people would be inclined, arguing from analogy with a solid, to reply that it would be reasonable to expect the drop to flatten itself, and even very considerably flatten itself, and then, collecting itself together again, to rebound, perhaps as a column such as we have seen, but not to form this regular system of rays and arms and subordinate drops. ”

“ It is impossible for either the eye or the mind to compass the whole mass of falling water; you cannot measure, cannot estimate its enormous volume; and this is the reason, perhaps, why travellers often express themselves disappointed by it. But fix your eye upon one portion—one falling and heaving wave out of the millions, as they turn over the edge of the rocks ”

“ It is like distributing the water of a pond among a multitude of shallow reservoirs—it covers more ground, and presents a greater surface to the rays of the sun, and it is precisely for this reason that it is all the sooner absorbed, evaporated, and lost. ”

“ Again, as in a building, If the first plumb-line be askew, and if The square deceiving swerve from lines exact, And if the level waver but the least In any part, the whole construction then Must turn out faulty—shelving and askew, Leaning to back and front, incongruous, That now some portions seem about to fall, And falls the whole ere long—betrayed indeed By first deceiving estimates: so too Thy calculations in affairs of life Must be askew and false, if sprung for thee From senses false. ”

“ We may conceive this pressure to arise from the tendency which the bubble has to contract, or in other words from the surface-tension of the bubble.
If to increase the area of the surface requires the expenditure of work, the surface must resist extension, and if the bubble in contracting can do work, the surface must tend to contract. The surface must therefore act like a sheet of india-rubber when extended both in length and breadth, that is, it must exert surface-tension. ”

“ Anon some wrinkled, fidgety, cogitative being in human form would add a new volume to some slope or tower of the monstrous omni-patulent mass, or some sharp-glancing youth, with teeth set unevenly on edge, would pull out a volume, look greedily and half-believingly for a few moments, return it, and slink away. ”

“ These then are the two methods by which the energy of the system will manifest itself in work. The one, which is much the more important for our purposes, leads always to a diminution of surface, to the so-called “principle of minimal areas”; the other, which leads to the lowering (under certain circumstances) of surface tension, is the basis of the theory of Adsorption, to which we shall have some occasion to refer as the modus operandi in the development of a cell-wall, and in a variety of other histological phenomena. ”

“ If we draw a line upon the primitive surface, dividing it into parts which represent respectively stable and unstable equilibrium, in respect to continuous changes, i.e., dividing the surface which is concave upward in both its principal curvatures from that which is concave downward in one or both, this line, which may be called the limit of essential instability, must have a form somewhat like that represented by in figure 2. ”

“ But, on the other hand, if an impressible person, standing alone over the brink of one of these processions, should behold it, not in its atoms, but in its aggregate,—as a mighty river of life, massive in its tide, and black with mystery, and, out of its depths, calling to the kindred depth within him,—then the contiguity would add to the effect. ”

“ When one is exhausted it is filled up and another is opened hard by—a deplorable system, as one hundred cubic metres must be displaced to examine one, and around each well a surface of twenty times the area is rendered useless. ”

“ Of course we are: but there is a universal balance throughout nature, and everything finds its level. There is order, when there appears disorder—and no stream runs in one direction, without a counter stream, to restore the equilibrium. ”

“ To prevent movement of the earth at the back of a wall pushing or fracturing it and being the cause of a slip, it may be well to briefly state a few points to which attention should be especially directed. ”

“ We receive the impression of the falling of a large mass of water, descending always from the same height and with the same difficulty. The scattering of the drops of water, the formation of froth, the sound of the fall by the roaring and by the froth, are constantly produced by the same causes, and, consequently, are always the same. ”

“ Every one has observed those sloping declivities, composed of the washings of torrents, the débris of precipices, and what may be termed the constant drippings of perpendicular eminencies and which lie like broad buttresses at their feet, forming a sort of foundation or basement for the superincumbent mass. ”

“ It is as if a swift stream were falling into underground channels below the mill of our being, where it could churn and roar away to waste. But some of it is led off at a higher level, and we can learn to lead off still more ”

“ In laying out a plan for draining land of a broken surface, which inclines in different directions, it is impossible to make the drains follow the line of steepest descent, and at the same time to have them all parallel, and at uniform distances. ”

“ It is true that now and again streams are found flowing in the direction of a fault, but that is simply because the dislocation is a line of weakness, along which it is easier for the denuding forces to act. ”

“ The barrier they had set up with so much toil was tumbling and collapsing in great gaps where the hungry current flung against it, but it held just long enough for them to raise another wall, longer, higher, firmer than the other and built with the frantic haste of desperate men. ”

“ Here and there, fronting the rest, stands a semicircular mass, as it were a huge grindstone, one half buried in the earth, or a pile that looks like a weatherbeaten, buttressed wall; and, raised by the slope of the ground, you see the tops of other masses, continuing away to the rear. ”

“ We see it turn hither and thither, and wonder that we took not a course more direct to our end. We perceive that we have gone far out of the way; but the obstacles are not seen that were, or seemed insurmountable--the stream, too deep to be forded--the rock, too high to be scaled--the thicket, too dense to be penetrated ”

“ Growth may cease at this limit, and a balance be struck; or the form of the unit may be altered and surface gained by flattening out, or very frequently by ramifying processes; or—and this the most frequent solution—the cell may divide, halving its volume, gaining new surface, and restoring the balance. ”

“ Whenever a tenacious water-holding stratum rests on a loose, gravelly bed so situated as to admit of a free discharge of water from or through it by means of the outcropping of the bed at a lower level, or of deep-lying conduits leading to distant points of discharge, superficial waters may be carried off by opening a passage for them through the impervious into the permeable stratum. ”

“ It has come down to us in anything but absolute purity—like a stream which has been made turbid by its earthly channel. The lower serves its purpose as a stage to the higher, then it falls away, the higher surviving. ”

“ The sharp angles and asperities of surface which they may have originally presented, are soon worn away; the matter constantly removed by the agency of water from their sides and summits is deposited at their feet; their elevation gradually diminishes, and even the inclination of their strata becomes at length obscure or wholly undiscoverable. ”

“ When the stretch is of a certain amount, there is equilibrium—the action of the spring just balances the weight,—and if the spring be stretched further there will be a balance of pull developed tending to bring the system back towards the equilibrium position. ”

“ The reader will easily convince himself that in an exact treatment of the equilibrium of such a double bubble we must recognize a certain negative tension in the line of intersection of the three surfaces of discontinuity. ”

“ I apply the term merely to signify loose and water-worn strata not at all consolidated, and deposited by an inundation of water, and in these countries which they have covered man certainly did not exist. ”

“ As seam unites to seam, and layer to layer, stratum upon stratum, so the systems almost insensibly unite, and forms of life appear, mature, and die away as the babe grows into the man, and dies away again to old age and final extinction. ”

“ Disturbances of equilibrium, resulting in rock movements under gravity, may be caused by local loading, either natural or artificial. Natural loading may be due to unusual rainfall, or raising of water level, or increased barometric pressure. ”

“ And when we find the columns of these buildings carved and moulded to look like groups of pillars embracing each other to gain strength, the salient parts of the construction grooved and striped, and the extremities of the clustered pillars spreading after the manner of a fan, over our heads; we are amazed at the manner in which mass and volume have been volatilized, spiritualized, and apparently dissipated. ”

“ The required width of the formation must be principally regulated by the character of the earth, the amount and suddenness of the rainfall, the height of an embankment or depth of a cutting, the degree of exposure, the exigencies of the traffic, and the required drainage. ”

“ These depths, constantly bridged over by a structure firm enough in spite of its lightness and of its occasional oscillation in the somewhat vertiginous air, invited on occasion, in the interest of their nerves, a dropping of the plummet and a measurement of the abyss. ”

“ If it goes up in the middle, flows over at the top and comes down at the outside and then flows into the middle again, why could it not keep on doing that all the time, until the balance was put straight again? ”

“ These little heaps, which are raised by degrees, give way to permit the eruptive matter to escape, and afterwards fall in, when the tertiary formations are exhausted, in a space of time of greater or less duration. ”

“ The plain below the point of issue from the mountain is rapidly raised by newly-formed torrents, the elevation depending on the inclination of the bed and the form and weight of the matter transported. Every flood both increases the height of this central point and extends the entire circumference of the deposit. Other things being equal, the transporting power of the water is greatest where its flow is most rapid. ”

“ And there are longer swells, begotten of drainage, sometimes of eight or ten feet in a mile, which deceive you, as you advance, into the expectation of a grand prospect when once you shall have got to the top of them. ”

“ On watching for a short time, it will be seen that these ridges are being raised higher and the ripple growing stronger; until at length, the action becoming violent, the whole series of ridges is suddenly swept away, the stream runs smoothly, and the process commences afresh. ”

“ Our stratification is like the ocean, where every individual [Pg 399] drop is free to move, and where from the sternest depths of the mighty deep any drop may come up to glitter on the highest wave that rolls. ”