Artificial Warmth.
PASSING from the direct to the indirect comforts of a household, we will take Artificial Warmth.
The savage, as a matter of necessity, makes a fire in the middle of his hut, and lets the smoke have its own way. Sometimes, as is the case with the North American Indians, the top of the conical hut is open, and the whole edifice is a single chimney of large dimensions, something like the “chimney-corner” of past days, which only survives in such places as the New Forest.
Then there are the various Kafir tribes of Southern Africa. They have no aperture in their huts except the tiny doorway, which can only be entered on hands and knees. But they must have their fire. No argument can persuade them that they had better make their fire and cook their food outside the hut. So the wood-smoke fills the hut, coats it with a lining of soot, and gets out as it can through the sticks and withes of which the simple edifice is built.
As a contrast, we have the oil-lamp of Esquimaux-land, where there is no provision for ventilation, where the snow-houses are tightly closed and crammed with inhabitants, and where no one seems to need fresh air.
The next step in civilisation is to construct a tube for the purpose of carrying off the smoke, such as we know by the name of chimney or flue, and to place the fire within it. We English people have an ingrained love for the open fireplace, and though it really is an expensive arrangement, it is worth the cost. Granting that it carries much of the heat into the chimney instead of throwing it into the room, it has at least the advantage of acting as a ventilator, of ejecting air which has been rendered poisonous by respiration, and drawing a fresh supply from the outer atmosphere.
In some parts of the world, especially in Germany and the United States, the place of the open fire is taken by closed stoves, without any ventilation whatever, much to the discomfiture of ordinary Englishmen. Still, there are buildings, such as public halls and places of worship, in which open fireplaces are wholly impracticable, and where it is, therefore, necessary to make use of the stove.
It need hardly be said that in such cases the chief object is to procure the greatest amount of heat with the least expenditure of fuel, and that object seems to be best attained by the Laminated Stove shown on the right hand of the illustration.
In this stove, the outer surface, instead of being plain, is divided into a number of perpendicular plates, which are heated by the contained fire, and expose a very large surface of hot metal to the air. Thus the heat, instead of being wasted by being drawn through the flue or chimney, is thrown into the room, and keeps up a perpetual supply of warm air.
That the invention of this stove is an ingenious one nobody can deny. But Nature has been long in advance of Art in the way of exposing as large a surface as possible with the least expenditure of space.
Very familiar examples of this structure may be found in the many creatures which inhabit the waters and breathe by means of gills, which extract the oxygen of the water.
Take, for example, a Lobster or a Crab, open it, and look at the white, pointed, uneatable objects which are popularly called “ladies’ fingers.” These are the gills, or breathing apparatus, and their structure is really wonderful. They are composed of innumerable laminæ, or very thin plates, covered with an exceedingly fine membrane, and placed closely side by side, but with sufficient distance between them to allow the water to percolate the whole structure.
With the aid of an ordinary pocket lens the observer may make out a most wonderful system of blood-vessels, which permeate every one of the myriad laminæ, and which extract the life-giving oxygen from the water as it passes between them.
Then, to pass to animals of a higher order, take the gills of fishes. Any fish will do, provided that it be fresh, and, if it can be examined immediately after death, so much the better. Taking things reciprocally, the gills of the fish and the laminæ of the stove, are identical in principle, namely, the exposure of much surface with little loss of space.
If possible, the observer should inject the blood-vessels of the gills with the conventional crimson and blue wax, showing the currents of the arterial and venous blood. Each lamina forms a most wondrous object, and may be gazed upon for weeks with increasing admiration.
Every one who has watched the habits of fishes must have noticed that in running waters they always have their heads against the stream, and do not greatly care about shifting their positions.
In still waters, especially such as those of the ordinary glass aquaria, the fish are perpetually on the move, whereas in such a river as the Dove of Derbyshire, and even the Darenth of Kent, large trout may be seen almost motionless, but invariably with their heads directed up the stream.
The reason is evident enough. As long as the fish lies with its head up the stream the water flows through its gills, and enables it to breathe. Were the passage of the water stopped, the fish would be drowned. Consequently, all good anglers, when they hook a fish which is worth taking, keep its head down the stream, prevent the water from washing over its gills, and consequently render it so weak by deprivation of oxygen, that it becomes an easy prey, and is rendered subservient to a line of a single hair. Let the fish breathe, and a single struggle would smash a line of treble the strength. But keep it from breathing by directing its head down the stream, and it rapidly loses all strength, and can be directed into the landing-net, or brought within the scope of the gaff, without a chance of escape.
I need hardly remark that on the right-hand side of the illustration is shown a Laminated Stove, and that on the left are drawings of the gills of the Shark tribe and the common Trout. If the reader would really like to look into the subject for himself, I should suggest the purchase of a cod’s head and shoulders and a lobster. The breathing apparatus can be removed from each for examination, and the remainder will serve as a first course for dinner.