The bench-wall forms were set in position, after they had been moved ahead, by first blocking the bottom against the face of the foundation, as shown by Fig. 13. As previously noted, this foundation face had been built very carefully to line. The back end of the form, of course, was blocked tightly against the end of the previously finished section, and the top was made plumb by the adjusting screwjacks shown in Fig. 16, _B_. At first these screws were ¾-in., but they were afterward changed to 1¼-in. The only points which it was necessary for the alignment corps to give in setting these forms was a grade at each of the front ends for the top of the finished bench. The steel face forms in both tunnels gave excellent results, as far as smoothness of finish was concerned, but, owing to the imperviousness of the steel, small air holes were formed in the surface, though not in sufficient numbers or size to cause trouble or disfigure the work in any way. The design of the bench-wall forms used at the western end, where this differs from the steel form, is shown by Fig. 16, _D_. The principal features in which they differed from those used at the Weehawken end was in the substitution of 2½-in. tongued and grooved hard pine for the face. This timber was of the very best quality obtainable, each piece being especially selected and as nearly clear and free from knots or other defects as it was possible to get it. The edges of each piece were planed at the back so as to insure a tight joint on the face, and all joints were shellacked. These forms were used, without renewal of the face timber and with only two planings, for a length of 2,500 ft., or 100 separate sections, and gave good satisfaction. In order to obtain a surface to which the face lagging could be fastened, wooden uprights were used and were reinforced on either side by light channels bolted together through the timber, in place of the =I=-beams used on the steel forms. The lagging was nailed to these uprights by 6-in. wire nails driven through the top edges of each piece as it was placed in position, thus leaving the surface entirely clear and free from any marks or nail holes, and in condition for planing when this became necessary. Runways for wheeling the concrete were built one either side over the bench-walls instead of having a center platform with chutes, as was used at Weehawken. When the original lagging had become too much worn for further use, it was resurfaced with strips of ⅞ by 2½-in., clear, tongued and grooved, hard pine, placed vertically, which did fairly well and lasted to the end (about 1,000 ft.), although it was not altogether satisfactory, and the last eight or ten sections built had to be rubbed down with a wooden float in order to obtain a suitable finish.