At one end of the furnace house there is sunk in the cement floor a large iron scoop or tray into which cartloads of lump coal are dumped. This scoop-shaped receptacle is also the platform of a weighing machine so that each load is weighed. In the bottom of the scoop there is a trap-door, which, being opened, permits the coal to drop through between the teeth of a crusher where the large lumps are reduced, usually to the size of a small nut.
From the crusher the coal falls into the buckets of an endless chain-hoist and is conveyed aloft to great hopper-shaped bins which occupy the entire space under the roof over the furnaces. Leading back from each bin to the constantly moving grate bars of the furnace underneath is a pipe which delivers the crushed coal to the grate bars and distributes it evenly over their surface as fast as it can be received into the furnace, regulated, of course, by the consumption that is going on inside the furnace.
To accomplish this automatic feeding each set of grate bars is constructed in hinged sections, and forms a wide endless iron belt which revolves and carries the coal within the cavity of the furnace.
The coal crusher, bucket hoist, movable grate bars, ash collectors and sifters, pumps, blowers, lights and all other utilities of the plant, as well as the great travelling crane which can hoist and carry many tons' weight--any part of the enormous dynamos--from place to place, are operated by electricity which is generated in the dynamos.
Automatic gauges that measure and indicate, and switch-boards that regulate the energy created and stored in the dynamos play important parts in the economy and working of the plant and are analogous to appetite and taste in man.
The full analogy may be best illustrated by arranging the similar functions of the two energy-creating machines opposite each other in parallel columns.
Selection of fuel as to Selection of food for steam-making and economic nutritive value; normal qualities. appetite serving as an exact guide and gauge.
Crushing coal so as to Masticating food so render combustion as that the juices of the easy and complete as mouth can act on the possible. substance with greatest freedom; taste being evidence of the working of the process.