This section is from the book "Health", by W. H. Coefield.
Considering that two-thirds of the surface of the earth is covered with water, if any difference is effected at all it is clear that a very considerable difference must be made in the climate of places by proximity to the sea.
After height above the sea, the most important consideration, as Humboldt tells us, is the distance from the sea: that happens in this way; the rays of the sun penetrate the waters of the ocean to a great depth, and the heat is, as it were, lost in the body of water; the ocean water has the highest capacity for holding heat, the rays of the sun penetrate to a great depth, and so the water and the air over it are very little heated. On the other hand, the rays of the sun heat the land, which absorbs heat readily, and the air over the land gets heated during the day, so that during the day the air over the land and the land get hot, and the air over the sea and the sea are very little heated, and so the pressure of the air over the sea is greater than over the land, therefore, during the day the breeze blows from the sea towards the land. During the night the earth gets very cold; the sea does nothing of the kind; it radiates very little, and so the sea and air over it change very little in temperature between day and night; during the night, therefore, a breeze blows from the land towards the sea. So the farther the land is from the sea the less it is affected by the change of air due to proximity to the sea. The sea exercises an equalising influence over the temperature of the land, and places near the sea have an equable temperature.
London is a good deal north of Paris, but it is near the sea, so London has a comparatively equable climate, while Paris has a climate of extremes, a very hot summer and a very cold winter. Paris sometimes has very cold winters indeed, on account of its distance from the sea. The Channel Islands, on the other hand, are very equable in climate. So places near the sea have the advantage of having their air changed very frequently, and it is, I make no doubt, one of the reasons why London and its neighbourhood are naturally such healthy places.
The sea air contains a large amount of moisture, as you would expect, dissolved in it, and sometimes suspended in it, and so places near the sea-side are moist places, and places which are exposed to winds passing over a large area of sea are moist places. That is why the west coast of England is moister than the east.
Diseases like dysentery, plague, cholera, ague, and so on, do not travel across even very narrow pieces of the sea, and so it is the habit in countries where these diseases are prevalent to have hospital ships placed at a little distance from the coast, and it has been frequently noticed, that while troops on land have been decimated by some of these diseases in hot climates, the sailors in the harbours have not suffered at all.
A word about stagnant waters.
When I tell you that two-thirds of the Europeans who die in hot countries, die of diseases that have been generated in marshy places, you will understand that it is an extremely important matter. When you consider that the oriental plague, which killed so many millions of people in the middle ages started in the marshes at the mouth of the Nile-that cholera commenced in the marshes of the Ganges-that yellow fever commenced at the mouth of the Mississippi-and that various kinds of ague are prevalent in marshy countries of all the temperate climates in the world, and extremely prevalent in many parts of Europe, you will see that this matter is one of great importance. Marshes may be found wherever a somewhat impervious soil exists, so that the water cannot get away by natural drainage; it does not at all matter how the water gets there : it may get there by rain, by the usual overflow of the river, or by the flow of a river being obstructed by the deposit brought down by it, for great rivers frequently bring down much solid suspended matter. In each case the result is the same, there is stagnant water, profuse vegetation, and one or other of these pestilential diseases is engendered, the worst forms of these diseases being found in the marshes of tropical climates. The precautions which people who work in marshy countries, for instance in cutting down forests or making railways, should take are-that they should live on as high a piece of ground as they can get; the windows should be away from the prevailing wind, especially if it blows over marshy land: they should never sleep on the ground, as it has been noticed over and over again that persons sleeping on the ground are much more liable to get such diseases than those who sleep even in hammocks above ground ; they should eat moderately, and especially of well-cooked food,-should not drink water from the marsh, or if they must do so, should boil it first, or, what is still better, should make tea of it.
In many instances the marshy country itself may be made salubrious, and this has been done on a large scale all over the world; Lower Egypt is one of the most remarkable instances of this. Lower Egypt used to be most fertile and prosperous-it was the place from which all the arts and sciences originated, the place in which medicine was first cultivated, and in which attention was first given to sanitary science. Moses, who was "learned in all the wisdom of the Egyptians," gave us the most admirable code of sanitary laws ever issued. Lower Egypt was the place, indeed, from which started all our knowledge; a highly intellectual race inhabited it at one time. Later on, through neglect of drainage, it became the most pestilential swamp, the home of the plague, which ravaged the whole world.
Intermittent fevers used to be much more fatal in England than they are now. The Registrar-general, I see in his summary for ten years, draws attention to this fact, which is the result of increased drainage of soil, so that there is no doubt whatever, that by drainage, the death-rate from marshy diseases may be lessened to a very considerable extent.
I said that, according to Humboldt, height above the sea was the most important fact as regards the climate of a place, and the higher the place above the sea, the lower its temperature, until at last we get to the region of perpetual snow. You think it is a strange thing that the higher and nearer to the sun we get, the more the temperature is lowered, but the reason is that the air is so rare that it does not absorb the sun's rays; they pass through it. The higher you go the rarer the air is, and so each time you breathe you breathe in the same volume but less weight of air, and therefore less weight of oxygen, so in order to get the amount of oxygen which is required for the purposes of the system you have to breathe more times, and people who live high above the sea level always breathe more quickly, hence those who require their lungs exercised adopt the excellent plan of going up into the mountains.
The diseases prevalent in mountainous countries are those due to cold, such as lung diseases, rheumatism, and heart disease consequent on rheumatic fever, but they are more specially prevalent, not in exposed situations but in gorges and valleys, where the air is stagnant and damp: cholera and typhoid fever are rare in mountainous countries, and in many such places cholera has never appeared at all.
Cold, then, is an important consideration, and this leads me to say that things made of wool are warmer, because they allow less heat to get away from the body, and another reason is that they absorb the moisture of the skin much more readily than clothes made of cotton or linen.
Land which is covered with vegetation, other things being equal, is colder and moister than dry places, for we know that dry places when there is no vegetation at all are some of the hottest places in the world, as, for instance, the desert of Sahara.
A word or two about the condition of the soil itself. Soils may be divided roughly into pervious soils and impervious soils. Places built upon pervious soils such as gravel, sand, chalk, through which the water can penetrate are dry, and generally healthy: lung diseases, rheumatic diseases, and consumption, are less prevalent there. The diseases that are prevalent there are cholera and typhoid fever; they spread upon these soils, according to the theory of a great German hygienist, on account of the emanations which are given out of these soils under certain circumstances, but in England we believe that these diseases spread because people drink water from wells in the soil into which impurities have percolated!
Upon impervious soils the disease that is especially prevalent is consumption, and on all undrained soils, whether pervious or impervious, this disease, the plague of temperate climates, is prevalent Dr. Buchanan has shown that there are no instances among the cases investigated, where the level of the water in the soil beneath the houses has been lowered by drainage, in which the death-rate from consumption has not been lessened, and in one town in England it was lessened fifty per cent. Various lung diseases and rheumatic affections are also prevalent on damp soils. It is exceedingly important that we should live upon dry soils, and there should be in every house what is called a damp course, a little distance above the ground all round the wall, of asphalte or glazed stoneware, so that the moisture cannot rise up through the walls. It is very important, too, that the basement of all houses should be impervious to water; there should be a layer of asphalte or concrete, all over the basement floor, above which the boards should be laid, and, if possible, there should be a ventilated air-space between the floor and the asphalte or concrete, so that no damp can rise up into the house; another reason for that is, that all soils contain a certain amount of air; pervious soils contain a good deal, and that is air which should not be admitted into the house, as it contains a large amount of moisture %and organic matter, which may be very foul.