In order to obtain a safe tenure for the main chains, the extreme links are enlarged and pierced with eyes, through which strong iron bolts are passed, constituting a species of framework, and the whole mass imbedded securely in the solid rock. The sixteen chains are formed into four lines of suspension, extending one thousand seven hundred and fourteen feet in length; five hundred and seventy-nine and a half of which form a catenary curve, between the pyramids, from which the roadway is suspended. A weight of six hundred and thirty-nine tons, nineteen hundred and nine pounds, is suspended between the pyramids, and the estimated weight of the iron work, from one extremity of the suspension chains to the other, amounts to two thousand one hundred and thirty tons, eighteen hundred being of wrought iron and only three hundred and thirty of cast. To give the iron work a fair bearing in their respective chambers, the following precaution was adopted: each bar and pin were wrapped in flannel, saturated with white lead and oil, and, to establish close and impenetrable joints, Borradaile’s patent felt was introduced between them, eight thousand superficial feet of which were consumed in this manner. The floor is composed of three strata of planks, the first three inches in thickness, the middle and the lowest two inches each, layers of patent felt being introduced between the planking strata. Twenty-four thousand seven hundred and ninety feet of felt were consumed in the roadway alone. Screens, or trellis-work of light bars protect each side, and permit the breezes to pass freely through; and a hand-rail of African oak directs and confines the hesitating steps of the foot passenger. The floor of the suspended part frequently assumes an arched appearance, which is not its original form, but arises from a contraction in the chains on the land side of the pyramids, the effect of which, being diffused equally over the chain of the suspended part, causes a temporary elevation of the roadway. It must be remarked that the sixteen main chains recline on saddles on the summits of the pyramids, without being attached to them, whereby every contraction or expansion which may occur on one side is communicated to the other, and over the whole, without any danger of rocking or disturbing the masonry. In the construction of the stone arches the same care and scientific knowledge are displayed which characterize every part of this noble work. The arches on each side, adjacent to the main piers, are semicircular, the others are less segments gradually diminishing as they approach the land: the crowns continuing parallel to the roadway admit a handsome entablature and cornice. A beautiful marble, raised at Penmon in Anglesea, is employed in the mason work, and Aberdaw lime was used in bedding the blocks that were laid under water.