Caul

“ The severity of the atmosphere and the rapid evaporation from the earth cause an increase of frigidity, to which the salts and nitrates upon the surface of the soil, by absorbing the hydrogen of the atmosphere—as is shown by the dampness of the ground and the absence of dust around the Saleratus Lakes—greatly add. ”

“ The coarser sandy layer just above the finest clay records the spring break-up, the melting of the ice, and resuscitated streams flowing from the hills with a vigor that can be acquired only when the melt-water from the winter snow combines with the normal run-off. ”

“ A bluish or gray vapor is constantly rising from the canals, the rivers, the sea, and from the saturated soil: a universal haze forms a soft gauze over objects, even in the finest weather. Flying scuds, like thin, half-torn white drapery, float over the meadows night and morning. ”

“ The entire substance of the contracting rock may be filled with liquid, pressed into it so as to fill every pore;--or with mineral vapor;--or it may be so charged at one place, and empty at another. There's no end to the "may be's." But all that you need fancy, for our present purpose, is that hollows in the rocks, like the caves in Derbyshire, are traversed by liquids or vapor containing certain elements in a more or less free or separate state, which crystallize on the cave walls. ”

“ Water is no exception. If finely divided, as by placing it in fine capillary tubes, in the pores of wood, or in the narrow spaces of a wick, it may be cooled several degrees below normal freezing-point. In a cloud, or fog, all the conditions necessary for surfusion to take place are undoubtedly present. The water is pure, the envelope is uniform, the subdivision is exceedingly minute, and the drops are free from most of the mechanical disturbances which bring about the solidification of larger masses in the laboratory. ”

“ The vapor is taken from the surface water; the surface water thereby becomes more salt, and, under certain conditions, heavier; when it becomes heavier, it sinks; and hence we have, due to the salts of the sea, a vertical circulation, viz., a descent of heavier — because salter and cooler water from the surface, and an ascent of water that is lighter — because it is not so salty from the depths below. ”

“ When the wind blows, which it is apt to do, dust fills the air. Much of the soil seems to be as fine as flour and very light when it is very dry. We rode for hours without seeing a drop of water, in creek or lake. ”

“ The rainfall may be divided into three parts: the first DRIES UP, being discharged into the air by evaporation either directly from the soil or through vegetation; the second RUNS OFF over the surface to flood the streams; the third SOAKS IN the ground and is henceforth known as GROUND or UNDERGROUND WATER.
THE DESCENT OF GROUND WATER. Seeping through the mantle of waste, ground water soaks into the pores and crevices of the underlying rock. All rocks of the upper crust of the earth are more or less porous, and all drink in water. ”

“ When a cavity is bored into, it may be rammed full of clay, and the boring continued through the clay; or if sufficient depth has been obtained, the charge may be placed upon the clay, which will prevent the wasteful dissipation of the gases. ”

“ The heated air over our fields and streams, in Summer, is loaded with moisture as the sun declines. The earth has been cooled by radiation of its heat, and by constant evaporation through the day. By contact with the cooler soil, the air, borne by its thousand currents gently along its surface, is condensed, and yields its moisture to the thirsty earth again, in the form of dew. ”

“ In some parts of the earth the precipitation is greater than the evaporation; thus the amount of water borne down by every river that runs into the sea may be considered as the excess of the precipitation over the evaporation that takes place in the valley drained by that river. ”

“ On a frosty night pools of water are covered with a hard, transparent crust, of what is called ice. You may break this crust into pieces, but if the cold continues, a new crust will soon be formed with bits of the old one firmly cemented in it. And the greater the cold the thicker will the crust be, until perhaps the whole of the water in the pools may become solid. ”

“ Water, a solid substance, heat, a beginning putrefaction, appear indispensable to the production and propagation of the animalcules; and such conditions are in fact always united. Without moisture, they never live; a solid substance must offer a basis to moisture, and, according to physical laws, the contact of the one with the other generates heat, and only by the simultaneous action of moisture and heat can putrefaction take place. ”

“ Although the gaseous matter first absorbed would soon be condensed, and part with its heat, yet the continual arrival of fresh supplies from below might, in the course of ages, cause the temperature of the water, and with it that of the containing rock, to be materially raised; the water acts not only as a vehicle of heat, but also by its affinity for various silicates, which, when some of the materials of the invaded rocks are decomposed, form quartz, feldspar, mica, and other minerals. ”

“ Instead of carrying the heat of the air, and of the surface of the ground, to the subsoil, the rain only adds so much to the amount of water to be evaporated, and increases, by so much, the chilling effect of evaporation. ”

“ Between them, the surface waters, laden with carbonic acid obtained from the atmosphere and from [5] vegetation, have for ages made their way, enlarging them by both chemical and mechanical action, till they have become fissures capable of giving passage to an enormous quantity of water. So from one joint to another, from one bedding plane to another, the water percolates downwards until it meets with some impermeable rock beneath, or until it finds an outlet at the level of the Secondary rocks forming the valley below. ”

“ Felling of forests.—The felling of forests has been attended, in many countries, by a diminution of rain, as in Barbadoes and Jamaica.998 For in tropical countries, where the quantity of aqueous vapor in the atmosphere is great, but where, on the other hand, the direct rays of the sun are most powerful, any impediment to the free circulation of air, or any screen which shades the earth from the solar rays, becomes a source of humidity; and wherever dampness and cold have begun to be generated by such causes, the condensation of vapor continues. ”

“ Couloirs and gullies are obvious funnels upon which wandering stones concentrate. In a snow or ice-backed couloir we must study the difference between the ominous furrows made by stones or those made by water. In a rock gully we have to look out not only for stones that may use it as a channel, but for all that its weathering walls may contribute on their own account, or that the changes of temperature, or even the disturbance of our own passage, may dislodge from the balanced accumulations. ”

“ The chief source of supply for water which falls on the earth is from the ocean. The heat of the sun raises a vapour from its surface. This vapour condenses and falls as rain or snow, either on sea or land. Rain after falling for some time is almost pure and for that reason is called soft. Hard water contains various minerals. ”

“ The centre of the couloir was occupied by a deeply-scored trough, evidently a channel for stones and avalanches, while the space on either side was so narrow that in case of a large fall we could scarcely expect to escape unharmed. Looking up to see what was likely to come down, we discovered at the very head of the couloir a perpendicular or slightly overhanging wall of névé, some 30 feet in height, and lower down, projecting over the rocks on our left, an enormous mass of icicles, on which the sun was playing, and, of course, momentarily loosening their tenure to the rocks. ”

“ A calcarious earth deprived of its air, or in the state of quick-lime, greedily absorbs a considerable quantity of water, becomes soluble in that fluid, and is then said to be slaked; but as soon as it meets with fixed air, it is supposed to quit the water and join itself to the air, for which it has a superior attraction, and is therefore restored to its first state of mildness and insolubility in water. ”

“ Suppose a geyser-tube filled with water, and heated at its lower end. As the water is heated below, convection tends to distribute the heat throughout the column of water above. If convection were free, and the tube short, the result would be a boiling spring; but if the tube is long, and especially if convection is impeded, the water at some level below the surface may be brought to the boiling-point earlier than that at the top. ”

“ When dry weather comes, soils lose water by evaporation with different degrees of rapidity. In this way a siliceous sand will give off the same weight of water in the form of vapour, in one-third of the time necessary to evaporate it from a stiff clay, a peat, or a rich garden mould, when all are equally exposed to the air. ”

“ For in these regions the water is everywhere: in the air, on the earth, and under the earth, where it appears barely a metre beneath the surface as soon as the crust of soft clay that it raises in blisters is lifted. ”

“ While if the land be so water-logged that the level at which water can be obtained by digging is brought near to the surface, the water containing salts from below is drawn upwards by means of capillary attraction, and once more evaporation takes place, leaving the salts in the soil. ”

“ Occasionally the soil is impregnated with saline or bitter particles, which are not tasted when the lakes are fresh filled by the rain, but which after a large evaporation render the diminished waters quite undrinkable. The rate of evaporation in these open plains, under a hot sun, and in the strong winds that often sweep the surface, is almost incredible. ”

“ In order to conduct the salt water to the circumference, small passages, or gutters, are made in the loose muddy earth, which lead it to the borders, where it is collected in holes, or salt wells, dug in the ground, for the purpose of evaporation. ”

“ So much for the mechanical action of rain, in the shape of ice. Now a few words on its chemical action.
Rain water is seldom pure. It carries in it carbonic acid; and that acid, beating in shower after shower against the face of a cliff—especially if it be a limestone cliff—weathers the rock chemically; changing (in case of limestone) the insoluble carbonate of lime into a soluble bicarbonate, and carrying that away in water, which, however clear, is still hard. Hard water is usually water which has invisible lime in it ”

“ In consequence of the effects of mountains in cooling currents of moist air, and causing the condensation of aqueous vapor in the manner above described, it follows that in every country, as a general rule, the more elevated regions become perpetual reservoirs of water, which descends and irrigates the lower valleys and plains. ”

“ In the early winter the cold air cools the surface waters of a lake. The cooling increases the density of the surface water causing it to sink, and allowing the warmer layers below to rise and become cooled. ”

“ The beds of coal were separated by strata of sandstone or compact clays, and appeared crushed under the weight of overlying strata.
At the age of the world which preceded the secondary period, the earth was clothed with immense vegetable forms, the product of the double influence of tropical heat and constant moisture; a vapoury atmosphere surrounded the earth, still veiling the direct rays of the sun. ”

“ If, on the other hand, we increase the pressure on the surface of the water by any means, such, for example, as by placing it in a chamber of compressed air, the water can be heated to a higher temperature without boiling away. ”

“ The great beds of salt, deep in the earth, are usually accumulations left there by water that is drawn from brine lakes, from which the liberated water often escaped as pure spring water at the surface of the earth. It does not escape by evaporation, at least not until it reaches the earth's surface. ”

“ The water from which the salt is extracted is pumped up from wells sunk in all directions round the place, and is conducted by pipes and channels into extensive pans, where, exposed to the action of the sun and air, the process of evaporation is soon completed. ”

“ Floods of a different character—due to the subsidence of the land so that it is partially covered with lake- or sea-water, which beats on its shores and erodes it in the manner already described—are also important factors in the transportation of clays. ”

“ But if an abundant supply of liquid or gaseous water is combined with cold sufficient to condense it into the solid form, it becomes fixed, and if the summer heat is insufficient to melt the excess of snow, it necessarily 295 accumulates. ”

“ The consequence of the ancient evaporation, by which the great Pleistocene lake was reduced to its present modest dimensions, and of the ceaseless modern daily evaporation, is the impregnation of the waters of the lake with salts and other mineral substances to a remarkable degree. Ocean water contains on an average 4-6% of salts: Dead Sea water contains 25%. ”

“ Heat seems to be the principal cause of the solution of many other bodies, as common salt, or blue vitriol dissolved in water, which when exposed to severe cold are precipitated, or carried, to the part of the water last frozen ”

“ The sources of chemical action in the earth are numerous. Water percolating through the soil, and finding its way to great depths through fissures in the rocks, carries with it oxygen and various salts in solution. Water again rising from below, whether infiltrated from the ocean or derived from other sources, is usually of a high temperature, and it always contains a large quantity of saline matter. ”