Page:The Building News and Engineering Journal, Volume 22, 1872.djvu/227

. Marcu 15, 1872. THE BUILDING NEWS. 211 i nn, — hence the shape and size of our apertures is an important consideration in the problem. A circular aperture or opening may be assumed abstractly to be the most natural form for admitting a quantity of light, as one allowing of equal diffusion of the rays on all sides. Circular openings, however, are expensive, and do not so readily adapt themselves in construction as square forms. Square apertures, also, are best adapted for lighting square or rectangular apartments— the angles of a square window allowing the corners of the room to be lighted more effi- ciently. Assuming, then, the square shape to be best, the question of the proportion of such a window may be urged, or whether an equal-sided square form is better than an oblong. Here, again, a little reflection will convince us that as the solar rays are gener- ally thrown in a slanting or oblique direction, and during a great portion of each day, from a point in or near the zenith, an exactly equal square (assuming no reflection or dif- fusion of light) would only admit a very limited portion of the rays, and this would be confined to a small part of the floor im- mediately under the window. On the other hand, a rectangular opening of two or three widths high will greatly increase the lighting area, and that, too, in the right direction, by allowing the rays to spread further inwards. Having arrived, at least approximately, at what we may term the common-sense principles of a window or light-giving aperture as far as form is concerned, its relation to the structure of which it forms a part has to be looked to. Its reference to the apartment must be brought into the problem, namely, whether it is merely to give light and ventila- tion, in which case a skylight is the most reasonable form if obtainable, or whether it has also to serve the purpose of an outlook as well as a light-giving window. In the last case, the oblong proportion of the opening recommended becomes also the most con- venient. It should always be recollected that windows receive a greater share of direct light the higher they are placed in reason, and ventilation also is facilitated. Out-look and ventilation then, combined with good lighting power, indicate a high-proportioned window in general cases within a moderate distance from the floor and also from the ceiling. Other special considerations may determine, in some instances, modifications of such a type, as in galleries of art, museums, law courts, churches, and other public buildings, the element of outlook being unnecessary in such. In these, clerestory or roof-lighting gives the most advantages, and makes a larger amount of wall space or area of room ayail- able. Such considerations, then, should funda- mentally regulate the design of these public structures; but I will speak more of these general arrangements by and bye. We have now considered a window in its two principal functions as a light-admitting and an out-looking opening, with relation also to the apartment. It has other relations which must not be overlooked, less general and abstract, but still important—namely, its relation to construction. The more general or primary conditions of a window, or any other feature, however, overlap, if I may be allowed the term, or are so connected with special or constructional ideas or neces- sities in architecture that it is difficult to draw a line where the one ends and the other begins. It would be often impossible for an architect, after he had laid down with some degree of precision the principles which should determine a window, or the lighting of his structure upon purely abstract or scientific data, to make up his mind to carry this idea out without reference to his materials or the construction to be adopted. In practice he finds often considerable limita- tions or restrictions to his most cherished theories, which show that while he is con- ceiving or thinking out his design he should be translating, as it were, his ideas into the more concrete sphere of construction, or bricks, stone, timber, and other materials. But to continue our solution of the: problem. A window must be considered in its rela- tion to walls and roofs, and here as before, first generally, 7.c., having regard to the primary object of a window and its general materials and construction; and, secondly, with regard to details of workmanship, &c. The general form and position of opening we have determined. As walls are necessarily thick, it is a question whether such an open- ing should be formed in or cut through them at right angles to its face or obliquely. A little thought will show that the most efficient manner of letting in light without increasing the size of the opening (large openings of glass being generally productive of cold rooms) is attained by splaying the sides of the opening both internally and externally (see Fig. 1). For appearance a square reveal is often preferable externally, while it gives facility in construction, and is less expensive. FIGS WE MOST EFFICIENT. FORM OF LIGAT — ADAUT.TING § QUTLOOKING APER TURES ™“. SON p * Lb EEN 6 Fig. 2 shows that by reducing the depth of outer square reveal greater compass of light and prospect is obtained with the same width of opening. Sectionally, Fig. 3 shows a similar splay at the head of the window, a very desirable expedient in con- tracted thoroughfares, where light is chiefly obtainable from the sky. A good splay to the window-sill is also desirable, both for throw- ing off the wet and for giving a larger angle of vision downwards. The size of window openings may here be discussed. ‘To lay down any determinate rule would be super- fluous, as different circumstances have to be considered in almost every case, though an aperture that is large enough to allow of moderate artificial reduction by blinds in the quantity of light is better than one which is barely large enough without such limitation. Palladio lays down the rule that their breadth should not be less than a fifth, or greater than a fourth, part of the breadth of the apartment ; that their height be double their breadth, with an additional sixth part of it. If there be more stories than one a re- duction of one-sixth part of the height to be made to the opening above. Next, the matter of construction as applied to walls of various materials is to be consulted. It is evident that in stone and brick walls some means are necessary in supporting the the superincumbent weight of material, either by a lintel, which is the simplest means, or by an arch. Either admits of considerable variety of form or treatment, bearing always in mind the principles just laid down. ‘The principal points in these lintels or heads is the soffit or under side, as any treatment or orna- mentation which interferes with the free in- gress of light from the sky is a fundamental mistake. Square or straight heads are best for simplicity and adjustment of blinds, shutters, &c.; they also are most economical, and suit better small apartments, while ex- ternally they can be treated in a manner as both to afford strength and effect. Stone, nally suggest themselves assuitable materials. Flat segments or canted heads seem to come next in order of simplicity, and may be variously modified; they are, moreover, stronger and more agreeable in appearance than straight, and the same remark applies to all arched forms of openings. When we see, however, monstrous relieving arches, mouldings and keystones piled on the top of an aperture just for the sake of ornament, or what is nearly as bad, heavy projecting en- tablatures shutting out the best part of our daylight, the whole thing becomes ridiculous. It must be borne in mind that the upper parts of a window opening, unlike a doorway, isthe most valuable part of it, and a too free inlet of light at this part can always be modified by artificial means. It may be thought from this that I would discourage tracery in windows. Certainly not, when this does not add unduly to obscuration, as some plate tracery does, and whena fair unobstructed area of opening is allowed; but insome apart- ments, where the tracery obscures a great portion of what ought to be open to give sufficiency of light, it becomes a farce. ‘‘ Dim religious light” is not our notion of this great and beneficent agent of Nature, and in many cases it would be far wiser to reverse the order, to conceal by tracery the lower portions of our window openings, however opposed such a course would be to precedent. But I am somewhat digressing ; this part of the subject belongs properly to the esthetic, or that step in the problem I shall presently deal with under the head of expression. We are now in a position to dis- cuss the filling-in of a window-opening or the means of shutting out the external elements, the inclemencies of the atmosphere, &c. Ex- perience has placed before us fixed bars of lead, iron, or wood, to which the glass is fixed with opening casements hung, pivot-opening sashes, and sliding sashes. Hither of these methods may frequently be adopted, though the pivot-hung and the sliding sashes are more convenient, and can be adjusted with greater nicety. The sliding or ordinary sash arrangement, however, is still im- perfect; the meeting-rails are incon- venient and unsightly, while the present mode of hanging by weights and lines will soon, it is to be hoped, be numbered among the things of the past. Before quitting this part of our subject I would mention the desirability of double coverings or sashes to our windows where practicable as a means of preserving equability of temperature in our rooms. The outer glazed sashes might in some cases project from the exterior face of wall where internal room is desirable. Blinds, shutters, and other artificial modes of obscuring the sun’s rays might next be adverted to if space permitted, but I think on the whole, and after some thought, ex- ternal shutters or blindsare far more rational, scientific in their operation, and useful, than inside ones. The sun’s rays are intercepted before they touch the glass or enter the room and are thrown off by reflection, while ex- ternal violence of all kinds, and noise, is averted or directly closed against. In my next I will discuss the last step in window design — expression, or xsthetic character. G. H. G. See gee PLUMBING.—VI. (Continued from page 200.) N last article the manner of covering “flat” on top of hipped or pavilion roof with lead was described, and supposing the length of flat had been taken at 116ft. instead of ‘¢ 16,” it would have been all the same as regards style, the only difference being that a greater number of pieces of lead would have been required. Had the breadth, however, been greater—say 30ft. in place of ‘¢12”’—then a division would haye been run up the centre lengthwise, something similar to what is to be explained below for zinc. And if broader still then drips would brick, terra-cotta, and even cast iron exter- ! also have been put in.