PREVENTION OF COLLISIONS. 



Hence it appears that 56 per cent, of these accidents arise from 

 collision. Next to these comes the escape from the rails by the 

 breaking of a wheel or axle, or by defective rails, which together 

 make up 32 per cent., the remaining causes operating in small 

 proportions. 



Since more than half the total number of fatal accidents which 

 occur upon railways arise from collision, it is important that the 

 attention of railway companies be more specially directed to 

 precautions against this source of danger. 



Before a collision takes place, the engine-driver and others in 

 management of the following train have, or ought to have, the 

 means of observing the object in advance of them, with which 

 the collision is about to take place. If it be possible to bring 

 the train to rest before it can pass over the length of road 

 between the point where the obstacle has been observed, and the 

 point where such obstacle would be overtaken, the collision will 

 be prevented. This possibility will depend upon the proportion 

 which the number of brakes and brakesmen upon the train bears 

 to its weight and speed. It is clear, therefore, that in all cases 

 the number of brakes provided should have reference to the 

 magnitude and speed of the train. 



It is found by experience that the distance within which a 

 train of given weight can be brought to rest by a given number 

 of brakes, will be in proportion to the square of its speed, that 

 is to say, with a double speed it will require four times the 

 number of brakes ; with a treble speed, nine times the number 

 of brakes ; and so on. 



In the case of an accident which occurred near Wolverton on 

 the 5th of June, 1847, it was found impossible to bring a train 

 of 19 carriages to rest within a distance of 540 yards, the speed 

 of the train being about 25 miles an hour. In this case a 

 collision took place by which seven persons were killed : on an 

 inquiry it was found that this train was provided with three 

 brakes, one upon the tender and two upon the carriages. 



28. Inquiries suggested by this and other similar accidents, 

 induced the Board of Trade to propose a rule to be observed by 

 railway companies, that a brake should be attached to every 

 fourth carriage. 



A similar rule was imposed by the French government, in 

 February, 1848, on the trains working on the railways of that 

 country. 



29. Since, however, the brake power necessary to stop a train 

 is increased in so large a ratio with the speed, a atill greater 

 number of brakes would be necessary with a fast train, such as 

 the express trains, each carriage of which ought to be provided 



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