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.]