In addition, five miles of buoy-rope were provided, besides buoys of different shapes and sizes, the largest of which (Fig. 38) would support a weight of twenty tons. As on the previous expedition, several kinds of grapnels were put on board, some of the ordinary sort, and some with springs to prevent the cable surging, and thus escaping while the grapnel was still dragging on the bottom; others, again, were fashioned like pincers, to hold (or jam) the cable when raised to a required height, or else to cut it only, and so take off a large proportion of the strain previous to picking up. Most of this apparatus was furnished by Messrs. Brown, Lenox & Co., the famous chain, cable, anchor, and buoy engineers, several of the grapnels being to their design, as well as the "connections." The propelling machinery of the Great Eastern had similarly received alteration and improvement in the intervals of the two expeditions. Moreover, the screw propeller was surrounded with an iron cage, to keep the cable and ropes from fouling it, as had been provided for the Agamemnon and Niagara in 1857. [Illustration: FIG. 38.--Buoys, Grapnels, Mushrooms--and Men.] The testing arrangements had been perfected by Mr. Willoughby Smith in such a way that insulation readings could be continuously observed, even while measuring the copper resistance, or while exchanging signals with Valentia. Thus there was no longer any danger of a fault being paid overboard without instant detection. On this occasion also condensers were applied to the receiving-end of the cable, having the effect of very materially increasing--indeed, sometimes almost doubling--the working speed. On June 30, 1866, the Great Eastern, steaming from the Thames--followed by the Medway and Albany--arrived at Valentia, where H.M.S. Terrible and Racoon were found, under orders to accompany the expedition. The Medway had on board forty-five miles of deep-sea cable in addition to the American shore end.