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.
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.