On several of the large rivers on the Continent, with rapid currents,
cable towage has been introduced in addition to the older methods of
transporting merchandise by sailing and steam boats or by towage with
screw or paddle tugs. A chain or wire rope is laid on the bottom of the
river bed, fixed to anchors at the ends and passed over a chain pulley
driven by the steam engine and guided by pulleys on the steam tug, the tug
lifting it out of the water at the bow and dropping it over the stern and
winding itself with the barges attached to it along the chain, the latter
being utilized as a rule only for the up journey, while down the river the
tugs are propelled by paddles or screws, and can tow a sufficient number
of barges with the assistance of the current. The system has been found
advantageous, as, although the power required for drawing the barges and
tugs against the current is of course the same in all cases, the slip and
waste of power by screws and paddles is avoided. The size of the screws or
paddles is also limited by the nature of the river and its traffic, and
with cable towage a larger number of barges can be hauled, while the
progress made is definite and there is no drifting back, as occurs with
paddle or screw tugs when they have temporarily to slow or stop their
engines on account of passing vessels. Several streams, as the Elbe,
Rhine, and Rhone, have now such cables laid for long distances in those
parts of the rivers where the traffic is sufficient to warrant the
adoption of the system. While this has been introduced only during the
last 16 or 18 years, a similar method of transporting merchandise has been
in use in Russia on the river Volga for upward of 40 years. Navigation on
this river is interrupted for about half the year by the ice, and the
traffic is of larger amount only during part of the summer, while the
length of the river itself is very great, so that laying down permanent
cables would not pay; while, on the other hand, the current is so strong
that towage of some sort must be resorted to for the transport of large
quantities. The problem has been solved by the introduction of the capstan
navigation or towage.
[Illustration: CAPSTAN NAVIGATION ON THE VOLGA.]
There are two kinds of capstans in use, one actuated by horse-power and
the other by steam engines. A horse capstan boat carries according to size
150 to 200 horses, which are stabled in the hold. On deck a number of
horse gears are arranged at which the horses work. The power of the
separate gears is transmitted to a main shaft, which is connected to the
drums that wind on the rope. The horses work under an awning to protect
them from the burning sunshine, and are changed every three hours. Eight
and sometimes ten horses work at each horse gear. The horses are changed
without interruption of the work, the gears being disengaged from the main
shaft in rotation and the horses taken out and put in while the gear is
standing. The horses are bought at the place of departure in the south of
Russia and resold at the destination, usually Nishny-Novgorod, at a fair
profit, the capstan boat carrying fodder and provender for the attendants.
The capstan is accompanied by a steam launch which carries the anchor and
hawser forward in advance of the capstan. The latter has a diameter of as
much as 5 in., and is two to three miles in length. The anchor is dropped
by the tug and the hawser carried back to the capstan, where it is
attached to one of the rope drums, and the boat with the barges attached
to it towed along by the horse gears described above winding on the
hawser. The advance continues without interruption day and night, the
launch taking a second anchor and hawser forward and dropping the anchor
in advance of the first by a hawser's length, so that when the capstan has
wound up the first hawser it finds a second one ready for attachment to
the rope drum. The launch receives the first hawser, picks up the anchor,
and passes the capstan to drop it again in advance of the anchor
previously placed, and carries the hawser back to the capstan, and so on.
A capstan tows twelve or more barges, placed in twos or threes beside and
close behind each other, with a load of a million pounds, or about 16,000
to 17,000 tons. From Astrachan and the mouth of the Kama the capstans make
during the season from the beginning of May to the end of July in the most
favorable case two journeys to the fair of Nishny-Novgorod; after this
time no more journeys are made, as the freights are wanting. At the end of
the up-stream journey the horses are sold, as mentioned before, and the
capstan towed down stream by the steam launch to Astrachan or the Kama
mouth, where meanwhile a fresh lot of barges has been loaded and got
ready, a new supply of horses is bought, and the operation repeated.
Besides these horse capstans there are steam capstans which are less
complicated and have condensing steam engines of about 100 horse power,
the power being transmitted by gearing to the rope drum. The rope drum
shaft projects on both sides beyond the boards of the boat, and for the
return journey paddle wheels, are put on to assist the launch in towing
the clumsy and big capstan boat down the river. The steam capstans tow
considerably larger masses of goods than the horse capstans and also
travel somewhat quicker, so that the launch has scarcely sufficient time
to drop and raise the anchors and also to make double the journey. We do
not doubt that this system of towage might with suitable modifications be
advantageously employed on the large rivers in America and elsewhere for
the slow transport of large quantities of raw materials and other bulky
merchandise, a low speed being, as is well known, much more economical
than a high speed, as many of the resistances increase as the square and
even higher powers of the velocity.
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