ss of capacity. They can be
used not only to carry light and heavy bodies, such as grain and coal,
in a continuous stream, but also to convey relatively large bodies such
as sacks of flour, or cement, &c., intermittently. Thus a band 26 in.
wide and 350 ft. long is used at a flour-mill in York to load sacks of
flour into railway trucks; by this means 12 wagons can be loaded by two
men in 1 hour. Band conveyors are not necessarily fixed in one place. A
portable model has rendered good service in tunnel-cutting, mining and
quarrying. This band is mounted in a light steel frame, itself fitted
with small wheels, so as to be readily put in any required position, and
is entirely self-contained, being provided with tightening gear, a small
motor, &c. If required, several lengths can be joined together, or one
band can deliver upon another at a lower level. The same advantages that
attend the use of the band-conveyor for handling grain may be claimed
for this appliance when carrying coal and heavy bodies, namely the
demand for relatively small power, smooth and noiseless work, and gentle
handling of material. On the other hand the feed cannot be withdrawn at
intermediate points except by means of a throw-off carriage. The
numerous bearings of the guide rollers require careful lubrication, and
the rubber bands should be protected as much as possible from changes of
temperature.

The _metal band_ or belt conveyor, a modification of the rubber or
canvas band conveyors, is an endless belt composed of iron plates
connected to endless chains, usually of malleable cast iron, running
under the plates. Such appliances, being obviously more cumbrous than
band conveyors, are only used in handling material of a hard and cutting
nature. They usually deliver only at the end, but if intermediate
delivery be desired a scraper may be so fixed across the band at a given
point, at an angle of 45 deg., as to scrape the whole or part of the feed
into a shoot, or a scraper may be mounted obliquely on a suitable
carriage which can be moved to any points at which delivery may be
required. In some bands of this type supporting rollers are attached to
the links and travel with them, or are fixed to the framing so that the
band runs over them, an arrangement which has the advantage of
economizing driving power and of promoting smooth running. Metal band
conveyors are tightened in the same way as textile or rubber bands, and
may run at a speed of 60 to 12