m. Double ropeways have been carried in one section over 18
to 20 m., and will transport single loads of 6 cwt. to a ton or more.

Broadly speaking, the single ropeway is not so suitable for heavy
loads and long distances as the double, but in this connexion the work
of Ropeways Limited should be noted, which favours a single rope
system. Their engineer, J. Pearce Roe, introduced multiple sheaves for
supporting the rope at each standard. Thus the rope may pass over one,
two or four sheaves, which are provided with balance beams that have
the advantage of adjusting themselves to the angle caused by the rope
passing over the sheaves, thus equalizing the pressure over a number
of sheaves. A ropeway erected on this system in Japan spans 4000 yds.
of very broken ground; yet only 17 trestles are used, and as each
support is placed as high as possible, no one is of great height. An
altitude of 1130 ft. is reached in a distance of 1200 yds. The ropeway
has a daily carrying capacity of 60 tons in one direction and of 30
tons in the other. Another installation on this system, which serves
an iron mine in Spain, spans 6500 yds. of very rough country, so steep
that in many places the sure-footed mule cannot keep on the track.
This ropeway can deal with 85 tons per hour. The greatest distance
covered by this system, on one section, is 7100 yds., or about 4 m.,
and the carrying capacity is 45 tons per hour.

The motive power required for a ropeway will vary with the conditions.
In cases of descending loads the power generated is sometimes so
considerable as to render it available for driving other machinery, or
it may have to be absorbed by some special brake device. In a ropeway
in Japan of 1800 yds., which runs mostly at an incline of 1 in 1-1/2,
the force generated is absorbed by a hydraulic brake the revolving fan
of which drives the water against fixed vanes which repel and heat it.
In this way, 50 h.p. is absorbed and the speed brought under the
control of a hand brake.

_Aerial Cableways._--The aerial cableway is a development of the
ropeway, and is a conveyor capable of hoisting and dumping at any
desired point. The load is carried along a trackway consisting of a
single span of suspended cable, which covers a comparatively short
distance. The trackway may either run in a more or less horizontal
direction, i.e. the terminals may be on the same level, or it may be
inc