CAOUTCHOUC 



711 



of the Government authorities at the Eoyal Arsenal, Wool-wich, and were in consequence 

 adopted for all kinds of military carriages, store waggons, ammunition waggons, &c. 

 They were also applied in the suspensory form for the medical cars and ambulance 

 waggons for the wounded, for which purposes the use of India-rubber on the prin- 

 ciple of extension is found to produce the easiest and most satisfactory spring hitherto 

 discovered. 



416 417 



418 



V 



When the material is used as a suspension spring, the most advantageous form for 

 the purpose is found to be that of round cord of the best and purest quality, prepared 

 by solvents, and about ^-th or |ths inch diameter. 



A continuous length of such cord is wound at a considerable tension over the ends 

 of two metal sockets or rollers, in shape something resembling a cotton reel, and 

 whilst in a state of tension, bound at each end with strong tape or other suitable 

 binding ; the number of cords composing the spring, varying from 10 to 20, 30, or 40, 

 according to the strength required. 



Another important adaptation of India-rubber by Mr. Fuller, is that of anchor 

 springs, towing ropes, and springs for the recoil of guns and mortars. 



Wheel tyres. Fig. 418 shows an important application to the 

 tyres of wheels for railway purposes. A thin band of India- 

 rubber is inserted between the tyre and spoke ring, by first covering 

 it with a thin plate of iron, to protect the India-rubber while the 

 hot tyre is put on, when the wheel is instantly thrown into water and 

 cooled. This has been severely tested for some time, and found to 

 . jj answer very well ; the advantage gained is the saving in the break- 

 ing and .wear of the tyres. 



For Windows. Small ropes of India-rubber are inserted in 

 grooves at each side of the window, and so stop out draught and 

 prevent noise. 



For steam-hammer beds. A plate of India-rubber $ths inch thick, is placed under the 

 bed of the hammer ; the effect is greatly to diminish the transmission of shocks to the 

 building, and to cheapen the foundation : as an instance of useful application, we may 

 state, that at Messrs. Ransome and May's works, at Ipswich, the working of the steam- 

 hammer shook the building and windows to an alarming extent ; but the insertion 

 of blocks of vulcanised rubber under the anvil, almost entirely obviated these effects. 

 Joints between engines and tenders. Messrs. Lund, Spencer, and Fenton, have also 

 introduced the use of rings of this material to form a joint between the locomotive 

 and tender (fig'. 419). They are extensively used, and entirely prevent the leakage 



419 



common to the old ball-and-socket joints, and are much cheaper in first cost. Kings 

 of India-rubber were proposed by Mr. Wickstead, for closing the socket joint of water 

 pipes, and they are used in a variety of forms for that purpose. 



A large trade has been established in the supply of bands of India-rubber for 

 driving machinery ; for many purposes they answer better than leather, water having 

 no effect on them and there being little or no slip and fewer joins ; they are made in 

 widths, and belts costing 1501. each have been used in some cases. They are made 

 with two or more layers of thread cloth between, and outside of which the rubber 

 is placed. 



