436 
rorULAR SCIENCE REVIEW. 
Steam Tmcage on CanaU , — In tlie use of steam-propelled vessels on canals 
great difHculty lias been experienced from the loss of efficiency of either 
paddle Tvheels or screws in confined channels. The water, driven hack by 
the propeller, necessarily placed in the stern, must be replaced by water 
flowing from the front through the narrow passages between the boat and 
the banks. If such a vessel is used as a tug, there is a disadvantage from 
the wash of the propeller being thrown on the bows of the vessels in tow. 
And the waves caused by the propellers seriously injure the banks. Mr. 
Max Eyth, of Leeds, in a paper read at the Institute of Mechanical Engineers, 
described a mode of propulsion by which these difficulties are overcome. A 
wire rope is laid in the bed of the canal from end to end, and anchored at 
its extremities. This rope is passed over a clip drum in the boat, and by 
means of an engine the boat is wound along by a direct pull on the rope. 
This system of clip drum and submerged rope was invented by Baron Oscar 
de !Mesnil and Mr. Max Eyth ; the first experiment with it was made at 
Leeds in 1866, and further trials had been made in Belgium and America. 
It had been applied on the Meuse from Namur to Liege, a distance of 
42 miles, and was being extended to Antwerp. The cost of towing only 
amounted to one-twentieth of a penny per ton per mile, including working 
expenses, management, and interest. The cost of towing by animal power 
is about seven times as great. With paddle tugs on the Thames the cost 
is nine times as great. The cost by screw tugs on English canals was five 
times as great. Mr. Ilawksley expressed an opinion that, for slow transit 
and heavy traffic, canals might advantageously compete with railways. 
Velocipedes . — Professor Bankine has communicated a series of articles on 
the theory of velocipedes to the pages of the Engineer. 
Channel Twmel . — The best means of improving the communication be- 
tween England and France has at last begun to receive serious consideration. 
Visionary projects of tunnels and bridges have been succeeded by carefully 
matured and well-investigated schemes put forward by competent engineers 
in sucli a form that the probabilities of success, in so vast an undertaking, 
may at least be seriously discussed. Mr. Hawkshaw has made a costly and 
careful survey and an examination of the strata by borings, which have 
satisfied him that a tunnel could be carried across the Channel entirely in 
the lower chalk. This material is one in which tunnelling is easy and 
rapid, and in which the risk would be limited to one contingency, namely, 
the possibility that the sea would find its way into the workings through 
some fissure. Mr. Hawkshaw estimates the cost at ten millions, and the 
time required for the execution of the tunnel at nine or ten years. lie pro- 
poses to test the probabilities of success by the construction of preliminary 
driftways. If these were safely carried across the certainty of success would 
be asstired. If they failed the los.s would not exceed two millions. 
More recently Mr. Bateman and Mr. Bevy have suggested a plan for con- 
stmeting an iron tunnel on the bed of the English Channel. The most 
interesting point about this scheme is the proposal to put the segments of 
the tube together in a sort of Iiuge diving hell, attached water tight to 
thn romph‘tp'1 part of the tunnel, and pushed forward by hydraulic presses 
as the work advances. This bell is to be a cylinder 80 feet long, 18 feet 
diameter, and would weigh in air 7o0 tons, in water 100 tons. The tunnel 
