Towing on the River Thames.

Steam was substituted for horse-power for towing on that portion of this river extending from London to Oxford, some years ago. Two tugs were furnished with engines of 30 and 40 horse-power, and feathering floats immersed three feet below the surface. These tugs frequently towed as many as ten barges from London to Richmond, where three or four were left, and the remainder taken as far as Oxford. The towing had to be done against a current in some places reaching 3 miles per hour. These steamers worked profitably for four years, until the traffic left the Thames and went to the Great Western railway.

The cost of towing was 18 mills per ton mile.

These tugs were sold to the commissioners of the river Severn. One was lost on the passage, the other, in 1866, was still at work.

Mr. Allen, who built these tugs, says: "Probably one of the greatest obstacles to the development of steam-power on the canals is the smallness of the locks, which generally admit of only two barges being locked at the same time."

The River Weaver.

Improvements in the navigation of this river were undertaken with the view of enabling it to compete with railways in the transportation of about a million tons of salt, together with the coal used in its manufacture. In a distance of 24 miles, 8 pools were formed, which were from 3 to 6 miles in length, and connected by locks. The locks were 100 feet long, 23 feet wide, and admitted vessels drawing 8 feet of water and carrying 150 tons.

It was found, however, that even with double locks, the delay with steam tugs towing several barges was so serious and so interfered with the traffic that the plan had to be abandoned.

In 1864, steam barges carrying their own cargoes were tried, and were so successful that others were afterward introduced. These barges were 85 feet long, 19 feet 6 inches beam, drew about 7 feet 6 inches of water, and carried from 180 to 200 tons each. With engines of 20-horse power, no difficulty was found in towing two or three barges carrying 100 tons each; but the locks were still a cause of serious delay. To remedy this difficulty, a third lock was built for each pool. These locks were 200 feet long and 40 feet wide, and enable each tug to take three barges through at a single lockage.

In 1866, horse towage was being abandoned on the Weaver, the last described steamers being considered to be most profitable.

The improved navigation has the following minimum dimensions of cross section: width at surface, 90 feet; width at bottom, 54 feet; depth, 12 feet.

Grand Junction Canal.

The steamer “Dart," upon this canal, was 70 feet long, 7 feet beam, and drew, loaded, 4 feet of water. She was fitted with a vertical,, high-pressure engine, the cylinder of which was 9 inches in diameter, and had 8 inches stroke of piston. The boiler was of the vertical flue type, 7 feet high and 4 feet 3 inches diameter, and its grate and heating surfaces were 5 and 120 square feet respectively. The screw was of the Griffith's patent, 3-bladed and 3 feet in diameter; and, with a boiler pressure of 75 pounds, the steam being cut off at half-stroke, made 180 revolutions per minute.

The "Dart" was designed to tow a single barge, and, between October 1st, 1864, and October 1st, 1865, steamed 11,280 miles, carrying and towing 3,182 tons. The working expense, including the engine and accompanying boat, was £366 138., or at the rate of 7.8 pence (144 cents) per train mile, or 0.184 of a penny (3 mills) per ton mile of cargo.

Aire and Calder Navigation.

The main line of this navigation extends between Leeds, Wakefield and Goole, a distance of 36 miles. The depth of water is 8 feet 6 inches in the canals, and 9 to 10 feet in the rivers. The width at top and bottom is 60 to 66 feet and 30 feet respectively; while on the rivers the surface width is 100 to 150 feet. The average sectional area is 380 (?) square feet. In the 36 miles there are 17 locks, having a total fall of 116 feet. In some portions of the canal, the banks were protected by dwarf slope-walls, having a depth of 13 feet of water against them.

Steam towage was introduced here as far back as 1836, and was at first conducted by means of paddle-wheel tugs, with high-pressure engines, having two cylinders 11 inches in diameter and a stroke of 20 inches. The paddle-wheels were 9 feet in diameter and 3 feet 6 inches wide. The speed attained with three boats carrying 100 tons of cargo was 3 miles per hour in the canals and 4 miles in the rivers. The cost per boat per mile was 8.516 pence (15 cents), and per ton mile 0.473 of a penny (8.56 mills).

In 1853, improved means of steam towage were introduced, which, in 1866, were still in use. These consisted of two systems, the one

that of the tug, carrying cargo and towing at the same time, and the other that of tugs having greater power, towing exclusively.

The dimensions of the first class, which was employed exclusively in merchandise traffic, were: Length, 63 feet 6 inches; beam, 12 feet 6 inches; depth, 7 feet 6 inches; capacity for cargo, 30 tons. The machinery occupied 20 feet of the after part of the boat, and consisted of high-pressure direct-acting engines, with cylinders 8 inches diameter and 12 inches stroke of piston. The boilers had 12 square feet of grate and 243 square feet of heating surface, and the working pressure was 100 pounds. The screw propeller was 5 feet 3 inches in diameter, 7 feet pitch, and made about 180 revolutions per minute. The traffic was conducted during the night at an average speed of 44 miles per hour, at which speed the banks sustained no injury. For the seven years preceding 1866, the average cost of towing was 2.125 pence (3 cents) per boat mile, and 0.085 of a penny (1.54 mills) per ton mile.

The second class of boats were similar in size to the first, and were employed solely in the general traffic of the canal. The whole space was devoted to the machinery, except so much as was set apart for the crew. The engines were direct-acting, had cylinders varying from 15 to 18 inches in diameter, and with strokes varying from 12 to 16 inches, and the working steam pressure was from 60 to 80 pounds. The boilers were return-tubular, and for the 16-inch cylinders had 163 square feet of grate and 920 square feet of heating surface. These tugs would tow 10 boats, carrying 700 tons of cargo, at 3 miles per hour on the canal and at 4 miles in the rivers. The charges for towing were of a penny (1 mills) per ton mile against the current, and of a penny (13 mills) down stream.

Still later, two

boats, carrying 160 tons, were fitted with steam power and put to work on this navigation, but with what results we are uninformed.

In 1866 a new plan was devised by Mr. Bartholomew for the transportation of minerals on this canal. This plan was thus described : "It consisted of a train composed of 7 rectangular boats, having their ends constructed with an outward curvature of 6 inches. The dimensions of the boats were: Length 20 feet, beam 15 to 16 feet, depth 7 feet 3 inches. Each compartment or boat was capable of carrying from 25 to 35 tons. When formed into a train, they retained their lateral position by means of a projecting stem which fitted into a corresponding hollow stern post. They were held together and steered by wire ropes which passed through suitable guides on each

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side, and which extended from the steam compartment at the after end to the leading or stem portion at the other. They were tightened by hydraulic power, and, when together, formed a train or vessel 190 feet in length. They were steered by two steam cylinders having their pistons in direct connection with the wire ropes, and were found to answer well in all respects. Each compartment was fitted with spring buffers at its corners." "The compartments were discharged by hydraulic power, which raised the compartment and its cargo, weighing about 42 tons, to the elevation required to suit the height of the ship. At this stage of the operation the compartment was gradually turned on its side and the contents discharged into a chute, and thence into the ship. In this way 100 to 200 tons per hour were shipped."

An examination was made of this canal after screw propellers had been in use upon it about 10 years, and it was found that no mischief had been done to the banks.

Steam has also been introduced upon the river Lee, the Shropshire Union canal, the Kennet and Avon, Leeds and Liverpool, and many other canals; but so far as steam trains are concerned, the results have been almost invariably unsatisfactory whenever there were numerous locks. The chief causes of failure have been the difficulties encountered in passing the locks, and in passing the shoal water sections where the resistance, on account of the restricted water-way, was necessarily greater than in water of fair width and depth.

The canals referred to, as well as foreign canals generally, are, as a rule, very small. The surface widths are, in many cases, not over 45 feet; while the depths, which in some cases are 5 feet and over, are generally not more than 4 feet. The sections of the water-ways are in some instances as small as 120 square feet, while even in many of the larger canals they do not exceed 150 feet. In introducing steam upon such canals, we can readily understand that serious, and sometimes insurmountable difficulties may be presented. Yet it appears that, notwithstanding these difficulties, steam navigation has, in some of its forms, been successfully introduced on many of these canals. It appears further, that the machinery used may be run 5, 7 and even 10 years with very trifling repairs, and hence that its endurance may be regarded as nearly, if not quite, equal to that of other steam. machinery.

The following table gives the lengths and dimensions of some of the English canals:

Prior to the general introduction of railways, the number of miles of canal-exclusive of improved rivers-in England alone, amounted to over 2,200.

In Holland and Sweden, too, steam has been successfully introduced, and is rapidly superseding horse-towage. At first, steam was used for towing simply, but the advantages of larger boats, carrying their own steam power, were soon discovered, and such boats adopted. The chief objection to these was, that the engineers were not constantly employed. This has been met by arranging steam-winches combined with the engines, by which the engineers are not only constantly employed while loading and discharging cargo, but these operations are accelerated to such an extent that the earnings of the boat are largely increased.

On nearly all the lines of Holland these steamers are understood to be paying well. They have increased in size from 35 feet in length to dimensions giving a capacity of 160 to 200 tons, which, however, are regarded as too large, and the tendency has recently been to return to boats carrying from 130 to 160 tons. These are 130 feet long, 16 feet beam, and draw 6 feet of water, having an ultimate capacity of 160 tons. The engines of these boats are of 25 horsepower, nominal, and their screws are 3 feet in diameter, having a pitch of 7 feet, and making 120 revolutions per minute.

In a great number of voyages, extending over a year and a half, between Rotterdam and Nymwegen, a distance of about 70 miles, these boats, towing a 70-ton barge, made a speed of 34 miles per hour against the current. The trip was usually performed in about 14 hours, giving an average speed of 5 miles per hour. The total cost