IlDproved Hall Joint and Base Plate. plate between the sleepers. The rails are secured to the base joints between the sheets (running up and down the slope) are at once fastened and rendered water.tight by half-round ribs of wood which are neatly covered with zinc by machinery, have two parallel longitudinal channels in their flat under side, to receive the turned-up adjacent edges of the zinc sheets. There is a little play for the zinc flanges in these channels, so that when the ribs are

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... d down, the metal can extend and contract with the changes of tempera ture so as neither to open seams by contraction or crowd up in waves by expansion. The transverse joints (parallel with the ridge of the roof) overlap of course, and have only to be secUl"ea each by a screw to the rib, and over this a neat molded cap, fitting the rib, is soldered to the edge of the upper sheet only. The appearance of the roof, with its ribs and caps in a regular figure, and its fl at surface at all times perfectly smooth, must be very neat and ornamental. Any device which shall lessen the enormous expense of replate and the base plate and clamp are fa stened together by pairs to the roadway and rolling stock of a road is valuable. gibs D, and split keys, E. The gibs are passed through the Much attention has lately been given to the subject, both in holes in the base plate and clamp, which correspond, and the Europe and this country, and there are a number of contrikey il'l driven through and spread on the other side, thus vances which, at least in part and temporarily, obviate this securing all firmly in place, as seen at F. trouble and improve the road . One of the greatest sources of