The feeding device is important as regards (1) damage to the material conveyed, (2) power required for operation, (3) initial cost and performance. The material may enter the conveying system by being (1) introduced directly into the fan (Fig. 8.1313), (2) sucked up by flexible hose (Fig. 8.13A) or (3) metered into the moving air stream by (a) a bucket- wheel, (6) an auger, (c) an injector, or (d) a column feeder (Fig. 8.14