e in
direct proportion to the use made of mechanical means of feed
conveyance. For instance, the store bins in connexion with such
elevators might be economically fed by suitable conveyors, or the
material might be brought in self-unloading hoppered trucks into
conveniently placed bins, ready to be drawn into the skips.

_Ropeways._--A ropeway has been defined as that method of handling
material which consists of drawing buckets on ropes, and by means of
ropes, such buckets being filled with the material to be handled and
being automatically or otherwise discharged. At what period of history
ropeways were first used it is impossible to say, but the fact that
pulley blocks, and even wire ropes, were known to the ancients, renders
a pedigree of 2000 years at least possible. In more modern days, an old
engraving shows a single ropeway in working order in 1644 in the city of
Danzig. This, the work of Adam Wybe, a Dutch engineer, was a single
ropeway in its simplest form, consisting of an endless rope passing over
pulleys suspended on posts; to the rope were attached a number of small
buckets, which evidently carried earth from a hill outside the city to
the rampart inside the moat. The rope was probably of hemp. Modern
ropeways worked with wire ropes date from about 1860, when a ropeway was
erected in the Harz Mountains. Since then several systems have been
evolved, but in the main ropeways may be divided into the single and
double rope class.

The ropeway is essentially an intermittent conveyor, the material being
carried in buckets or skips, and practice has proved it an economical
means of handling heavy material. The prime cost of a ropeway is usually
moderate, though of course it varies with the ground and other local
conditions. Working expenses should be low, because under the
supervision of one competent engineer unskilled labour is quite
sufficient. A ropeway may be carried over ground over which rails could
only be laid at enormous cost. To a certain extent ropeways are
independent of weather conditions, because their working need not be
interrupted even by heavy snowfalls. Their construction is very simple,
and there is little gear to get out of order. Sound workmanship and good
material will ensure a relatively long life. As an instance, a certain
rope in a Spanish ropeway tested new to a breaking strain of 29-1/2 tons
was shown after carrying 160,000 tons (in two years' incessant work)
still to possess a brea