The Window.
HAVING traced, though but superficially, the chief parts of a building, such as the walls, the door which is opened through the walls, and the roof which shelters them, we naturally come to the Windows by which light is admitted to them, and enemies excluded.
There are, perhaps, few points in Architecture in which such changes have been made as in the Window, which, instead of being a difficulty in the way of the architect, is now valued as a means of increasing the beauty of the building. Taking for example even such advanced specimens of Architecture as those furnished by Egypt, Greece, and Rome, we find that the Window is either absent altogether, its place being supplied by a hole in the roof, or that, when it is present, it was made quite subordinate to the pillars and similar ornaments of the building.
This fact is, perhaps, greatly owing to the influence of climate. In the parts of the world which have been mentioned in connection with this subject, light and heat appear to be rather enemies than friends, and the object of the architect was to enable the inhabitants of his houses to avoid rather than to welcome both. Consequently, the Windows were comparatively insignificant. They were not needed for the purposes of light or air, those being generally furnished by the aperture in the roof, and consequently were kept out of sight as much as possible.
But when architects had to build for a sterner, a colder, and a darker clime, where the sun never assumed that almost devouring heat and light which in hot countries drive the inhabitants to invent endless devices for obtaining coolness and shade, a different style of Architecture sprang up. In this the Window became nearly the most prominent part of the building: the elements were excluded by glass instead of stone, and the principal modifications of light were obtained by staining the glass in various rich colours. Perhaps the Window has attained its culminating point in the Crystal Palace, which is all window except its foundations.
Partly in order to enable the glass to be inserted, and partly to increase the beauty of the building, and to avoid the mean appearance of Windows filled in with plain iron bars crossing each other at right angles, the interior of the Windows was adorned with stone “tracery,” varying much according to the epoch of the building.
One of the most beautiful forms of the Window is that which is called the Wheel. The window itself is circular, and the tracery is disposed so as to bear an exact resemblance to an ornamental wheel, the lines of the tracery running from the circumference to the centre, just like the spokes of a wheel. One of these Wheel-windows is shown on the right hand of the illustration.
On the other side is an object, which at a hasty glance might be taken for another Window of the same character. It is, however, the work of an insect, and not of man, and is magnified in order to show its structure better.
Any of my readers who may happen to be entomologists or anglers, or both, are familiar with the Caddis-worm of our fresh waters. Most of us know that the Caddis is the grub or larva of the Stone-fly (Phryganea), an insect haunting the waterside, and so moth-like in its general aspect that many persons think that it is really a brown moth. The changes or metamorphoses of these insects are well worthy of notice.
In one respect the Caddis resembles the larva of the Wax-moth, mentioned on page [151], inasmuch as it has a soft, defenceless body, while the first three segments are comparatively hard. Like the Wax-moth also, the Caddis lives in a tube constructed by itself. Instead, however, of having a long and fixed tube, up and down which it can pass at pleasure, the Caddis makes a tube only a little longer than its body, and light enough to be carried about, just as the hermit-crab carries its supplementary shell. There are many species of Caddis-fly.
The Caddis inhabits fresh waters, and cares nothing whether they be ponds or running streams. In order to defend its white, plump, and helpless body from the fishes and other enemies, it constructs a tube around its body, strengthening it by a wonderful variety of material according to the locality.
Mostly the tubes are covered with little pieces of stick or grass, or leaves, while some species use nothing but sand-grains, constructing with them a tube very much resembling in shape an elephant’s tusk, and reminding the conchologist of the dentalium shell. But they seem to use almost anything that comes to hand. Taking only examples found by myself in a single pond, these cases are formed of sand, stones, sticks, grass-stems, leaves, shells of small water-snails, mostly the flat planorbis, the opercula of the water-snail, empty mussel-shells, a chrysalis of some moth which had evidently been blown into the water from an overhanging tree, and acorn-cups. The larva, however, does not seem to be able to fasten together any objects with smooth surfaces, and though it has been known, when in captivity, to make its cases out of gold-dust or broken glass, it could not use either material when in the form of beads.
When it is full-fed, and about to enter the pupal state, it proceeds to prepare its habitation. As a larva, when it desired to feed, it protruded its head and the front of its body from the mouth of the tube, and then crawled about in search of nourishment, dragging the tube with it, and holding it firmly by means of the claspers with which the end of the body is furnished. But when it becomes a pupa it is no longer able to defend itself, and is instinctively compelled to secure its safety in some peculiar manner.
It cannot fasten up the entrance entirely, because it would not be able to breathe unless water could pass over its body. Accordingly, it constructs a grated window precisely like those of the old castles, so that water can pass freely, while no enemy can gain admittance. Unlike, however, the grated windows of the castle, which had no pretence to beauty, the Caddis always constructs its barriers in some definite pattern. Each species appears to have its own peculiar pattern, but all agree in making their window, if we may so call it, exactly like a wheel-window before the glass is inserted.
When the pupa is about to make its final change into the perfect form, it cuts away the tracery with a pair of sharp jaws, with which it is furnished for this sole purpose, emerges from the water, throws off the pupa-skin, and issues forth as a Stone-fly.