Besides these, value in the mere material is a great element in architectural effect. We all, for instance, admire an ornament of pure gold more than one that is only silver gilt, though few can detect the difference. Persons will travel hundreds of miles to see a great diamond or wonderful pearl, who would not go as many yards to see paste models of them, though if the two were laid together on the table very few indeed could distinguish the real from the counterfeit.
When we come to consider such buildings as the cathedral at Milan or the Taje Mehal at Agra, there can be no doubt but that the beauty of the material of which they are composed adds very much to the admiration they excite. In the latter case the precious stones with which the ornamental parts of the design are inlaid, convey an impression of grandeur almost as directly as their beauty of outline.
It is, generally speaking, because of its greater preciousness that we admire a marble building more than one of stone, though the colour of the latter may be really as beautiful and the material at least as durable. In the same manner a stone edifice is preferred to one of brick, and brick to wood and plaster; but even these conditions may be reversed by the mere question of value. If, for instance, a brick and a stone edifice stand close together, the design of both being equally appropriate to the material employed, our judgment may be reversed if the bricks are so beautifully moulded, or made of such precious clay, or so carefully laid, that the brick edifice costs twice as much as the other; in that case we should look with more respect and admiration on the artificial than on the natural material. From the same reason many elaborately carved wooden buildings, notwithstanding the smallness of their parts and their perishable nature, are more to be admired than larger and more monumental structures, and this merely in consequence of the evidence of labour and consequent cost that have been bestowed upon them.
Irrespective of these considerations, many building materials are invaluable from their own intrinsic merits. Granite is one of the best known, from its hardness and durability, marble from the exquisite polish it takes, and for its colour, which for internal decoration is a property that can hardly be over-estimated. Stone is valuable on account of the largeness of the blocks that can be obtained and because it easily receives a polish sufficient for external purposes. Bricks are excellent for their cheapness and the facility with which they can be used, and they may also be moulded into forms of great elegance, so that beauty may be easily attained; but sublimity is nearly impossible in brickwork, without at least such dimensions as have rarely been accomplished by man. The smallness of the material is such a manifest incongruity with largeness of the parts, that even the Romans, though they tried hard, could never quite overcome the difficulty.
Plaster is another artificial material. Except in monumental erections it is superior to stone for internal purposes, and always better than brick from the uniformity and smoothness of its surface, the facility with which it is moulded, and its capability of receiving painted or other decorations to any extent.
Wood should be used externally only on the smallest and least monumental class of buildings, and even internally is generally inferior to plaster. It is dark in colour, liable to warp and split, and combustible, which are all serious objections to its use, except for flooring, doors, and such purposes as it is now generally applied to.
Cast iron is another material rarely brought into use, though more precious than any of those above enumerated, and possessing more strength, though probably less durability. Where lightness combined with strength is required, it is invaluable, but though it can be moulded into any form of beauty that may be designed, it has hardly yet ever been so used as to allow of its architectural qualities being appreciated.
All these materials are nearly equally good when used honestly each for the purpose for which it is best adapted; they all become bad either when employed for a purpose for which they are not appropriate, or when one material is substituted in the place of or to imitate another. Grandeur and sublimity can only be reached by the more durable and more massive class of materials, but beauty and elegance are attainable in all, and the range of architectural design is so extensive that it is absurd to limit it to one class either of natural or of artificial materials, or to attempt to prescribe the use of some and to insist on that of others, for purposes to which they are manifestly inapplicable.
VIII.—Construction.
Construction has been shown to be the chief aim and object of the engineer; with him it is all in all, and to construct scientifically and at the same time economically is the beginning and end of his endeavours. It is far otherwise with the architect. Construction ought to be his handmaid, useful to assist him in carrying out his design, but never his mistress, controlling him in the execution of that which he would otherwise think expedient. An architect ought always to allow himself such a margin of strength that he may disregard or play with his construction, and in nine cases out of ten the money spent in obtaining this solidity will be more effective architecturally than twice the amount expended on ornament, however elegant or appropriate that may be.