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them into the passing ; the rail on the oppo-site side having an opening for the ledge to passalong, as shewn in the rail Fig. XI.
Fig. IX. shews the sort of rail laid at thepoint when the four rails meet together, a beingthe point where two of the rails meet, and b cwhen they branch into two separate rails again ;the upright ledges d d and e e standing up about\ inch, prevent the wheels from running off theroad at the junction of the rails, where the pro-jecting ledge on the wheels has no effect inkeeping them upon the road. By attentiveexamination of these rails, on the larger scale,Figs. IX. X. and XI. and applying them to thelines of road shewn in a smaller scale in Fig.
XII. it will be seen in what manner the wheelsof the carriages are directed into the properroad. The moveable, or switch mil, is alwaysto be put into the proper position by the atten-dant of tlie train of carriages, to divert theminto the proper track, otherwise they wouldalways continue along the main line. Figs.
XIII. and XIV. Plate II. will shew two singlelines of road, with passings of a different kind ;A A', Fig. XIII. is the main line, extended thewhole distance, along which the carriages travel,in both directions ; B B' is a siding or passing,for the carriages going in opposite directions topass each other; this kind of siding is used