It was at one time intended to carry this progress still further by joining up the other two 51-foot furnaces, so as to make a single one 123 feet in length, but certain difficulties in the matter of bringing coke supplies to the two sides, under the special conditions of available floor space, and the disastrous effects of the financial panic of October, 1907, stopped all extension work for the time. Such extensions would however, present no real difficulties either in construction or in subsequent furnace management or operation. Figs. 35 and 36 indicate in plan and elevation the arrangement of the plant and accessories for these extended furnaces. Each 15-foot furnace had its own settler situated in front, and these have been retained without any change of position or any further additions. The hearth of the newly bridged portion slopes from the middle of the bridge to the tap-holes of the old furnaces, which still serve this purpose for the larger ones, and from which a continuous stream of matte and slag flows through a slag spout to the settler in front. The side water-jackets of the old furnaces remain, being built up in two sets of panels, each 7 feet 6 inches wide, whilst the new bridge portions are constructed of three sets of jackets, each 7 feet wide. [Illustration: Fig. 35.—Plan of 51-foot Blast Furnace, Anaconda, indicating Position of Crucibles, Spouts, and Connecting Bridge between Old Furnaces.] [Illustration: Fig. 36.—Longitudinal Section and Part Elevation of 87-foot Blast Furnace, Anaconda, indicating Crucibles of Old Furnaces, Bridge, and Jacketing.] The furnaces in their lengthened form have proved a tremendous success, far indeed beyond the anticipation of the designers and managers. This is largely due (_a_) To the increased efficiency and economy of replacing a number of smaller furnaces situated end to end by a single large furnace; (_b_) To the increased intensity of heat and reactions owing to large massed quantities of fuel burned at once, and to large masses of material being smelted and in a state of chemical activity. The advantages which result from such lengthening of blast furnaces are:— (i.) Gain in hearth area without extension of the blast-furnace floor and building. (ii.) Increase in smelting or hearth area and in consequent capacity, at a rate very much superior to the extra water-jacketing involved. Thus, in the 51-foot furnace, the capacity has been increased in the proportion of 3·8 to 1, the jacketed surface has increased only at the rate of 2·4 to 1. The output has increased at a much greater speed than was actually anticipated from the additional hearth area. (iii.) A very marked saving of fuel. The amount of coke required for similar charges has been reduced by one-tenth; more than 11 per cent. was required formerly on a charge, only 10 per cent. was necessary under the new conditions.