The successful lighting by day of a large roofed-in station will depend principally upon an appropriate distribution of the glazed portions. With a large span, and the glass skylights placed near the apex, the side lines and platforms will be much less efficiently lighted than those near the centre; and again, if the glazed parts are only at the sides, then the centre portion will be rather in the shade. Where possible it is better to place the glazed portions and slated portions alternately, so as to obtain a more uniform light all over the centre area, somewhat similar to the arrangement shown in Fig. 406. Roofs over passenger platforms at roadside stations are made in many types, the arrangement depending in a great measure upon the width of platform to be covered. In many of the earlier stations the roof was extended across from side to side, and included the lines of rails as well as the UP and DOWN platforms, a system which was not only costly, but had the disadvantage that the steam and smoke from passing 273 trains remained for some time under the roof before it was thoroughly dispersed. The more modern and more economical plan is to put the roof or shelter over the platforms only, and allow the steam and smoke to pass away into the air. In designing the latter class of roof, the fewer supporting columns the better, so as to diminish as far as possible the obstructions on the platforms. Where the platform is unavoidably narrow, the roof may be carried on curved brackets projecting out from the walls. Except in tropical countries, where shade is more acceptable than strong light, a liberal amount of glass should be provided in these platform roofs. On many of our home railways they are entirely covered with glass, and the abundance of light is found to be of great assistance in the working of the traffic. Figs. 411 to 420 are sketches of a few out of the many types of small roofs which have been erected over single and island platforms. Goods-sheds.--The form and dimensions of a goods-shed for any station must be determined by the description and amount of traffic to be transacted at the particular place. With an estimate of the traffic before him, the engineer must consider the internal arrangement of building most suitable for the bulk of the merchandise to be accommodated. The principal object of the shed is to permit of goods being transferred under cover from or to railway trucks or carts without being exposed to the weather, and the transfer will be expedited if the arrangements are made the most convenient for the particular class of merchandise presented.