is said to be that, although the peculiar combination of parts constitutes a striking and valuable novelty, it contains nothing that has not been proved by the experience of years—­nay, generations—­to be useful, economic, and reliable.  The usual practice followed in erecting suspension bridges is applicable in mounting the line, and the carriers, supports, and carriages may be of any of the usual forms.  For the rapid removal of limited loads wire tramways are in universal favor, and are recognized not only as very economic and quickly constructed, but also as being in many cases the only means of transport available except by the adoption of elaborate and costly engineering works.

It has, it seems, been suggested by some who have examined the construction of the flexible girder tramway for mineral and produce traffic that it would be an additional advantage if arrangements were made for the carriage of small loads—­half a dozen or so—­of passengers, the primary intention being to carry the workpeople backward and forward between comparatively inaccessible mines, works, or plantations and a neighboring village or town.  Compared with every other system where the line over which the load travels is elevated, the flexible girder tramway is claimed to possess many advantages—­the center of gravity is kept well down, the liability of the wheels leaving the line is reduced to the minimum, the gradients are the easiest that can be obtained, there is an entire absence of jolting and extremely little vibration, and the motion is altogether smooth and regular; yet it is very questionable whether, when human life is at stake, any but an ordinary ground line should be relied upon.  A living freight is far more liable than a dead freight to move during the journey; and as the safety of all overhead lines depends upon what is scientifically designated “unstable equilibrium,” the flexible girder tramway is not recommendable for passenger lines, although it can, of course, be fitted for passenger traffic, a suitable vehicle and ten or a dozen good stout workmen coming well within a two-ton load, which can be readily carried.

[Illustration:  BALL’S flexible wire tramway.]

Rope traction or animal traction—­practically speaking—­is alone available for wire tramways (that is to say, if the trains are each to be propelled by its own locomotive—­whether steam, springs, or electricity—­the cost of construction and maintenance becomes so serious that overhead lines, however well designed, are no longer economic); and experience gained with rope traction in numerous collieries in the North of England and Lancashire districts—­where it is highly appreciated—­has shown that, all circumstances considered, the endless rope is preferable.  The chief objection urged against wire tramways as hitherto constructed has been that the “sag” of the rope has sometimes caused annoyance to those using the property passed over, and has always added