Fig 463 shows one type of water column for watering engines. The wide base-plate is bolted down on to a foundation of stonework, brickwork, or concrete, and the main supply pipe (not less than 7 or 8 inches in diameter) is carried up inside the column, and connected with the screw valve, A, which regulates the delivery to the tenders. The curved top, which forms the outlet, and carries a leather hose, works on a swivel joint, and can be swung round, either to the right or left, for convenience of supplying engines on one or two standing-lines. The delivery valve can be opened or closed by the 303 small hand-wheel B, which is conveniently accessible to the man on the tender. On the above sketch (Fig. 463) the water column is shown placed at an ordinary normal distance from the rails; but in cases where there is considerable space between the two lines of rails, or where a platform intervenes, the swinging arm may be extended out to the necessary length, and counterbalanced as shown in Fig. 464. CHAPTER VI. 304 Comparative Weights of some Types of Modern Locomotives. Weights of Locomotive Engines.--The demand for higher speeds of passenger trains, with more conveniences, luxuries, and consequent increased weights in the carriages, has naturally led to greatly increased power and weight of the locomotives devoted to the passenger service. Although these engine weights have so largely increased during the past twenty-five years, there is nothing to indicate that they have yet reached the maximum. The tendency is still to increase, and will doubtless continue, so long as the permanent way can be made to sustain such enormous rolling loads. Locomotives for goods trains have also increased in power and size, but perhaps not in the same proportion as those for the passenger service. There is not the same disposition to expedite the transit of goods and minerals, which do not deteriorate during a long journey. Perishable articles, such as fish, fruit, and milk, are usually conveyed by passenger trains, or trains set apart specially for the purpose. [Illustration: Fig. 465, 466, 467]