Porches, Eaves, and Windows.
We now come to some of the appendages of a house, namely, the Porch by which the rain is kept from a doorway, the Eaves by which it is kept from the walls, and the Windows which will admit light and air, but will prevent the entrance of intruders.
We first take the Porch, two examples of which are shown in the accompanying illustration, one being the work of human hands, and the other that of an insect.
The figure on the right hand represents an old-fashioned Porch, such as is often to be seen attached to old village churches, and which, being furnished with seats, serves also as a resting-place for those who are weary.
The figure on the left hand of the illustration is a wonderful example of the Porch, as constructed by insects. It is the nest of a honey-making Brazilian wasp named Myrapetra scutellaris. The peculiarity of this nest consists in its exterior being covered with a vast number of projections made of the same material as the walls of the nest, but more solid and much harder. The colour of the nest is blackish brown.
The object of all these projections has not been ascertained, but there is no difficulty as regards some of them. Without a very careful examination, it is exceedingly difficult to see any opening by which the inhabitants of the nest can go in and out. It will be found, however, that there are many entrances, which are set in a row round the nest, each opening being situated under a projection, which thus performs the office of a porch as well as that of concealment.
Another hymenopterous insect carries out the principle of the Porch in its nest. This is the Myrmica Kirbyi, a tiny reddish Ant which inhabits India. It makes its nest of cow-dung, which it works up into a texture very like that of an ordinary wasp-nest. A series of large flakes of this substance overhang the entrances, so that the inhabitants can enter freely, while rain is kept out. For the purpose of greater security, one very large flake covers the roof in umbrella fashion. The whole nest is globular, and about eight inches in diameter.
Next we come to the projecting Eaves, like those of our houses, and serving to preserve the body of the edifice itself from wet. On the right hand of the illustration there is an example of the eaves as they are still to be seen in some of our country places, where the less picturesque slates have not yet superseded the old thatch. In some places these eaves extend considerably beyond the walls, and I know of several instances, especially in North Devon, where a supplementary set of eaves extends, like a penthouse, throughout the length of the building, and just above the windows of the ground-floor.
The reader will remark that the projections upon the Myrapetra’s nest may very well fulfil the office of eaves as that of porches, and not only shelter the entrances, but serve to shoot the wet off the walls of the nest.
On the left hand of the illustration are several instances of eaves as existing in Nature.
In the centre is the compound nest of the Sociable Weaver-bird of Southern Africa (Philetœrus socius).
This is a dwelling constructed very much after the fashion adopted by many hymenopterous insects, namely, that each pair of birds make their own individual nest, but unite with their companions in constructing a common roof or covering. More than three hundred nests have been found in a single habitation, and sometimes the birds miscalculate, or rather, do not calculate the resisting power of the branches, and, when the rainy season comes, the additional weight of water brings down the whole edifice with a great crash.
The thatch which covers this congeries of nests is made of the Booschmannees-grass, whose long leaves and tough wiry stems are admirably adapted for throwing off water, even though they be not bound together like our more regularly constructed thatch.
Perhaps the reader may be aware that in the Orang-outan, the Chimpansee, and other large apes, the hairs of the arms are very long, and point in different directions, so that if the creature should be caught in a rain-storm, and, after the manner of its kind, fold its arms on its breast, with the hands resting on the shoulders, the rain is shot clear of its body, the hairs performing the duty of eaves.
Both Japan and China have a rain-cloak, constructed on exactly the same principle as the thatch of the Sociable Weaver-bird. They are nothing more than successive rows of long grass-blades fastened to a network of the proper shape. No amount of rain or snow can wet them through, and they have the advantage of being pervious to the exhalations of the body, though impervious to external moisture.
In this respect they are greatly superior to our waterproof coats, for, if the wearer has to undergo much bodily exertion, or is obliged to wear it for any length of time, he finds his clothing nearly if not quite as wet as if he had allowed the pure rain to fall on him from the clouds. I possess specimens of each kind of cloak.
When I procured them they were quite blackened with London smoke, and, on account of their resistance to water, washing them was a very long and troublesome business.
Above the nest are two patches of the Booschmannees-grass, as they appear when laid by the bird.
Below the nest is a group of the eggs of the Gold-tailed Moth, whose nest has already been described. Perhaps the reader wonders where the eggs are. Owing to the mode in which they are arranged, only a few can be seen, and are represented by the little white spots in the lower part of the figure. When the Gold-tailed Moth is ready for the great business of laying her eggs, she seeks a suitable place, and then piles them up in the form of a shallow cone. Her task, however, is not yet finished. Having arranged her eggs, she scrapes off the long downy hairs of the tail-tuft, and arranges them carefully on the eggs so as to cover them with a conical thatch, very much resembling that of an ordinary corn-rick.
The Brown-tailed Moth acts in a similar fashion.
Furs of various kinds act in the same manner, being impervious to wet during the life of the animal. Such, for example, is the fur of the Beaver, that of the Capybara, and that of the Seal, which are animals living in our time. These, however, are exceeded in their thatch-like powers by the three successive coatings of hair that were worn by the ancient Mammoth, the outermost being very long and very coarse, and hanging down in heavy tufts so as to shoot the water from them.
Being on the subject of roofs, we will take a few more examples of the roof as anticipated in Nature.
That parallel fibres, whether animal or vegetable, can throw off rain when properly arranged, has already been shown. Much more is it evident that flat or partly flat plates will have the same effect, if they be arranged so that the joints are “broken,” as masons and bricklayers say, i.e. so that the broad part of the upper row of plates overlaps the junction of two of the plates in the row immediately below it.
On the right hand of the accompanying illustration are given two sketches of a modern roof, one slated and the other tiled. The figures on the left show that this formation has been anticipated by Nature, in the wonderful system of scales which cover the wings of butterflies and moths, and to which all their brilliancy of colour is owing. In spite of their minute size, most being too small to be distinguished by the unaided eye, they are arranged as regularly as the best workman could lay the slates or tiles on a roof, and on exactly the same principle.
The shapes of these scales vary in almost every species, but they are always arranged on the same plan, namely, being placed in successive rows, each overlapping the other.
In consequence, it is almost impossible to wet a butterfly’s wing with water. The insect may be plunged beneath the surface, and the long hairs of the body will be soaked and cling together in a very miserable fashion. But the water rolls off the wings like rain off a slated roof, and even if a few drops remain on the surface, they can be shaken off, and the wing will be perfectly dry.
Mostly these scales are flat, but sometimes they are curved. I have among my microscopic objects a piece of wing from a South American butterfly, the scales of which are oblong and bent, just like the curved tiles shown in the second right-hand figure of the illustration. These beautiful scales are deep azure or warm brown, according to the direction of the light.
Perhaps my readers may call to mind that some architects dislike the flat, square form in which slates are usually put on roofs, and try to make them less formal.
Sometimes they take their square slates, and fit them with one of the angles uppermost, so that each slate looks something like the ace of diamonds in a pack of cards. Sometimes they are still more ambitious, and certainly succeed in producing a better effect, by cutting the slates in hexagons instead of squares, and fixing them as shown in the right-hand figure of the illustration. Putting aside the familiar hexagons of the honeycomb, and the apparent hexagons of an insect’s compound eye, we have in the common Tortoise an example of hexagonal plates that exactly resembles the slate roofing.
In the next illustration we have a variety of the same principle exhibited in differently shaped tiles and scales. The figures on the right hand show the pointed, the square, and the oblong tiles. These also would answer very well as representations of different forms of scale armour, the one being intended to throw off rain, and the other to repel weapons.
On the other side of the illustration are examples taken from the animal kingdom. First comes the Bajjerkeit, or Short-tailed Manis, which has already been mentioned, and whose imbricated scales will resist the blows of any spear or sword. As to my own specimen, when it is struck, it resounds as if it were a solid plate of metal, and I should think that during the lifetime of the animal a reasonably strong axe would not easily make its way through that coat of mail.
Below the Manis are a pair of fish, whose scales, though not so strong as those of the mammal, yet are arranged in the same manner, and answer the same purpose. The last figure represents three scale-bands of the Armadillo, an animal which has already been mentioned. I may as well state here that in several anthropological museums there are various portions of defensive armour made from the scale-clad skin of the Crocodile, Manis, and similar animals.
ARCHITECTURE.
CHAPTER III.
THE WINDOW.—GIRDERS, TIES, AND BUTTRESSES.—THE TUNNEL.—THE SUSPENSION-BRIDGE.
The Window, and its Modifications according to Climate.—Bars and Tracery.—The Wheel-window and the Caddis.—Curious Structure of the Caddis-tube.—Object of its Window.—The Girder as applied to Architecture.—The Radius and Ulna.—The Tie as applied to Architecture, and its Value.—Combination of the Tie and Girder.—Structure of the Crystal Palace.—Leaf of the Victoria Regia.—A Gardener turned Architect.—The Buttress in Art and Nature.—The Tunnel used as a Passage of Communication.—Natural Tunnel of the Ship-worm.—The Thames Tunnel.—The Piddock, or Pholas.—The Driver-ant.—The Suspension-bridge.—The Palm-wine Maker and his Bridge.—Suspension-bridges of Borneo and South America.—The Creepers and the Monkey Tribes.—The Spider and Little Ermine Caterpillar.