Chap. XXIV.
1419
The double loop is always to be preferred, and made by doubly twisting the Tope roundthe pole, passing it by the loops, and drawing them tight.
Chains made ofiron are oftenfound more con-venient in their ap-plication to ma-chinery, consistingof a scries of linksriveted in the man-ner of a watchchain, or hookedtogether, as pro-posed by M. Vau-
&
f
Fig. 2367.
Fig. 2388.
Fig. 2380 WATCH-CHAIN.
Fig. 2390.
YAUCANSON.
canson: each system, however, has its advantages and peculiar application.
CIIAP. XXIV.
MASOXRT.
Building with stone is of the greatest antiquity, and it is extremely difficult to traceits origin : the Egyptians were perfect masters in the art of stone-cutting, and the Greeksexhibit such perfection in their works, that it is almost impossible to equal them ; to themason’s art they added that of the sculptor, and the buildings executed in marble, stillremaining, are monuments of th^ir taste and skill. The Romans have also left much thatis worthy our admiration, particularly those structures in which arches and domes of con-siderable dimension form the striking features : to the freemasons of the middle ages weare also indebted for many wonderful examples of their ingenuity and knowledge, of whichwe have ample proofs in the well-executed groined vaults they introduced, and which areunequalled for design in the structures which preceded them : they lessened the area ofthe points of support, balanced the thrust of their stone roofs by judiciously conceivedbuttresses, and evinced great skill in their adaptation.
For facing the stone our masons now make use of the point, the inch tool, the broadtool, and the boaster ; the first is to form a series of narrow furrows, with rough ridgesbetween them, afterwards to be cut away by the inch tool. The boaster is 2 inches inwidth, and the broad tool 3^ inches at the cutting edge. Stone axes, jedding axes, cavil orscabbling hammers are employed to bring rough stones into shape; mallets and chisels,levels, plumb-rules, bevels and squares, are also required bythe mason.
The Opus incertum , formed of small stones of irregularshape, touching only at certain points, was preferred byVitruvius to the opus reticulatum, not on account of itsappearance, but for its superior strength ; if the mortar bewell composed for the materials with which the inner partof the work is filled, and the angles are protected withsquared or hewn stone, a solid mass will be the result.
The Emplecton had the faces of the stones smooth ; theother sides were left as taken from the quarry. Wallsare often built with flint or round stones from the sea-beach; it is then necessary to protect the quoins with squaremasses, and to carry up the outer faces by means of framesformed of planks, as has been described for pise work ; wehave many castle and city walls so built, that have acquired
Fig. 2391. opus 1NCEKTUM.