[Illustration: Fig. 345, 346, 347, 348, 349, 350, 351, 352, 353, 354, 355, 356] Fig. 346 shows an example of what is termed a _flying junction_, or a junction of two double lines arranged in such a manner as to cause the least interruption to a constant train traffic passing UP and DOWN over both lines. Upon referring to Fig. 345 it will be seen that a train from F, turning off at the points E and proceeding to G, must block, or close for traffic the section ABC during its passage over that line towards G. With a crowded train-service the blocking of both UP and DOWN main lines for the working of one train would cause much interruption, and to obviate such delay the _flying junction_ is substituted. Fig. 346 shows how a train from F is turned off at the points J and proceeds on to K, where by means of a bridge it passes either over or under both main lines, and 233 continues on to G without in any way interfering with the train service on ABC. Fig. 347 is an ordinary plain siding or _turn-out_, including the necessary throw-off or trap-points and short dead end. Fig. 348 is an ordinary _cross-over road_ from DOWN main line to UP main line, and _vice versâ_. Fig. 349 is a double cross-over road, generally termed a _scissors_ cross-over. Fig. 350 is a simple through cross-over road from DOWN main line to siding alongside UP main line. Fig. 351 is a similar arrangement of through cross-over road with the addition of a pair of slip points at S to make a connection with the UP main line, thus combining the facilities of the ordinary cross-over and through cross-over road. Fig. 352 shows a set of three throw-switches with all the sliding tongues placed side by side; and Fig. 353 shows another arrangement of three throws with the sliding-rails of the second set of switches placed just behind the heel of the first set of switches. The latter method works very well where there is sufficient length for the purpose. Fig. 354 shows a square crossing, where one line of railway crosses another line of railway on the same level. Fig. 355 shows a connection with a siding by means of an ordinary carriage or waggon turn-table. Fig. 356 shows a set of “runaway” points which are sometimes placed in the main line at the top of an incline close to a station, the object being to intercept or throw off any portion of a train which may have become detached, and which would, if unchecked, run away back down the incline. By means of a weighted lever or spring the points are set to the normal position of _open_ to the siding, and as they are “trailing” points for the running road they are readily closed by a passing train. One or other of the above forms of connections, or a combination of them, will meet all the requirements which usually occur in railway work. Fig. 357 is an enlarged sketch of an ordinary cross-over road, and Fig. 358 of a double or _scissors_ cross-over. [Illustration: Fig. 357, 358]