Modern Gasworks Practice

56 MODERN GASWORKS PRACTICE hold the advantage, in that the coal when deposited in. the store is at charging-level. With the medium- and larger-sized houses this cannot, however, be said to be of great importance, owing to the common use of some form of coal-handling plant. With small houses, wh.ere hand-chargirig is in vogue, the point is of some importance. The distance between the upper and lower floor-levels varies from 5 to 10 feet, the former being the allowance in very small subway houses ; but if adequate depth. is to be given to the producer, the lieight should not be less than 8 feet. As regards this, it will be seen from Fig. 13 that in the stage house the difference between the floor-levels accounts for a certain bulk of coal which has to be brought to the working Fig. 15. Travelling Floor for Subway Retort House. stage. This mcreases the cost of handling, unless the store is fitted with elevators for feeding overhead hoppers. This is not the case with the arrangement shown in Fig. 14.