708 



CAOUTCHOUC 



under sudden concussion, and occasioning complete disintegration of the material 

 where not breaking. 



409 



r 



To obviate these defects, George Spencer (in 1852 and 1853) proposed to mould 

 the caoutchouc at once in the form it assumes under pressure, and then to place a 

 confining ring of iron on the larger diameter. (See fig. 410). By this ingenious plan, 

 the caoutchouc loses its power of stretching laterally, being held by the ring b, secured 

 in a groove moulded in the cone to receive it ; -when the pressure is applied to the ends, 

 the rubber is squeezed into the cuplike spaces c, and thus the action of the spring is 

 limited. By this plan, rubber of a cheaper and denser kind can be used than on the 

 old cylindrical plan, and the patentee states that many thousands of carriages and 

 trucks are fitted with these springs which give entire satisfaction ; among which, are 

 those on the Brighton, South- Western, North London, South Wales, Vale of Neath, 

 Bristol and Exeter, Taff Vale, Lancashire and Yorkshire, St. Helen's, Bombay and 

 Baroda, Theiss Kailways, and many others. These cones are used as buffer-, bearing- 

 and draw-springs for railway carriages* and are made in several sizes to suit various 



410 



uses. To show the power that such springs are equal to, we append the result of an 

 experiment on a No. 1 cone (for inside buffers), 3 inches in length, 3| inches diameter 

 at ring, 5 inches diameter of ring. 



1st Experiment, without the confining ring, weight of cone l Ib. 



Inches Giving a stroke of 



Without any pressure the cono measured .3 . 



With pressure 280 Ibs. 2$ . . inch. 



448 Ibs. 2 . . . 1 



672 Ibs. li . . H 



2nd Experiment. 



With the confining ring b, on the same double cono; the following were the 

 results : 



Without any pressure the cone measured . 

 With 448 Ibs. 



1,680 Ibs. 



2,912 Ibs. 



15,680 Ibs. . 



3 inches, as before. 

 2 

 2 

 If 

 14 ,, 



