The Stones of Venice, Volume 1 (of 3)

by John Ruskin

The result of this operation will be of course that the shaft tapers faster towards the top than it does near the ground. Observe this carefully; it is a point of great future importance.

§ V. So far of the shape of detached or block shafts. We can carry the type no farther on merely structural considerations: let us pass to the shaft of inferior materials.

Unfortunately, in practice, this step must be soon made. It is alike difficult to obtain, transport, and raise, block shafts more than ten or twelve feet long, except in remarkable positions, and as pieces of singular magnificence. Large pillars are therefore always composed of more than one block of stone. Such pillars are either jointed like basalt columns, and composed of solid pieces of stone set one above another; or they are filled up towers, built of small stones cemented into a mass, with more or less of regularity: Keep this distinction carefully in mind, it is of great importance; for the jointed column, every stone composing which, however thin, is (so to speak) a complete slice of the shaft, is just as strong as the block pillar of one stone, so long as no forces are brought into action upon it which would have a tendency to cause horizontal dislocation. But the pillar which is built as a filled-up tower is of course liable to fissure in any direction, if its cement give way.

But, in either case, it is evident that all constructive reason of the curved contour is at once destroyed. Far from being an easy or natural procedure, the fitting of each portion of the curve to its fellow, in the separate stones, would require painful care and considerable masonic skill; while, in the case of the filled-up tower, the curve outwards would be even unsafe; for its greatest strength (and that the more in proportion to its careless building) lies in its bark, or shell of outside stone; and this, if curved outwards, would at once burst outwards, if heavily loaded above.

If, therefore, the curved outline be ever retained in such shafts, it must be in obedience to æsthetic laws only.

§ VI. But farther. Not only the curvature, but even the tapering by straight lines, would be somewhat difficult of execution in the pieced column. Where, indeed, the entire shaft is composed of four or five blocks set one upon another, the diameters may be easily determined at the successive joints, and the stones chiselled to the same slope. But this becomes sufficiently troublesome when the joints are numerous, so that the pillar is like a pile of cheeses; or when it is to be built of small and irregular stones. We should be naturally led, in the one case, to cut all the cheeses to the same diameter; in the other to build by the plumb-line; and in both to give up the tapering altogether.

§ VII. Farther. Since the chance, in the one case, of horizontal dislocation, in the other, of irregular fissure, is much increased by the composition of the shaft out of joints or small stones, a larger bulk of shaft is required to carry the given weight; and, cæteris paribus, jointed and cemented shafts must be thicker in proportion to the weight they carry than those which are of one block.

We have here evidently natural causes of a very marked division in schools of architecture: one group composed of buildings whose shafts are either of a single stone or of few joints; the shafts, therefore, being gracefully tapered, and reduced by successive experiments to the narrowest possible diameter proportioned to the weight they carry: and the other group embracing those buildings whose shafts are of many joints or of small stones; shafts which are therefore not tapered, and rather thick and ponderous in proportion to the weight they carry; the latter school being evidently somewhat imperfect and inelegant as compared with the former.

It may perhaps appear, also, that this arrangement of the materials in cylindrical shafts at all would hardly have suggested itself to a people who possessed no large blocks out of which to hew them; and that the shaft built of many pieces is probably derived from, and imitative of the shaft hewn from few or from one.

§ VIII. If, therefore, you take a good geological map of Europe, and lay your finger upon the spots where volcanic influences supply either travertin or marble in accessible and available masses, you will probably mark the points where the types of the first school have been originated and developed. If, in the next place, you will mark the districts where broken and rugged basalt or whinstone, or slaty sandstone, supply materials on easier terms indeed, but fragmentary and unmanageable, you will probably distinguish some of the birthplaces of the derivative and less graceful school. You will, in the first case, lay your finger on Pæstum, Agrigentum, and Athens; in the second, on Durham and Lindisfarne.