530 Mechanical Science. [Nov. 



The iron wheel, though«the same weight, or lighter than the common one in use, 

 is incomparably lighter and more elegant in appearance: to give sufficient strength 

 to wooden wheels, particularly in this country, they require to be made proportion- 

 ally clumsy ; this is particularly observable in the naves which exhibit an unseemly 

 conical block, so shaped to admit of the hoops being from time to time driven home, 

 as the wood shrinks, in the nave of the iron wheel no such deformity is presented. 



The material, being iron throughout, is not affected by the atmosphere, which in 

 India is found so destructive to wood, causing the necessity of frequent setting up 

 and constantly recurring outlay for repairs : even new wheels kept 12 months in 

 store, require to be set up before being brought into use, or sent on service. The 

 tire of the iron wheel is so firmly united to the nave, by the suspending rods or 

 spokes, that no working can loosen it — a defect wooden wheels are at all times, and 

 in all places, subject to. The tire or rim of the patent wheel is the only part liable 

 to wear out ; when this takes place to a certain extent, fresh tires may be applied, 

 as in common wheels ; such tires being put on at a red heat, over the cold rim, 

 grasp it by the contraction that takes place in the process of cooling ; almost as 

 firmly as if the parts were welded together. By this simple and expeditious ope- 

 ration, a wheel after 20 or 30 years' service may be put in condition to perform 

 as many more, with this difference however that the spokes are no longer capable 

 of being removed at pleasure, the heads being covered by the new tire ; but this 

 can be of little consequence, as such repaired wheels might be appropriated to wag- 

 gons or other carriages not usually exposed in action, or it might be found ad- 

 vantageous to withdraw the old spokes before applying the new tire, and then to 

 drill fresh holes for a new set of spokes, or for the old ones, with heads readjusted 

 to fit the holes, and thus a complete new wheel would be produced. These wheels 

 are not liable to injury from any concussion, however violent, because they yield 

 to a certain extent to the shock, space sufficient being left, within the cells of the 

 nave to admit of a recoil or spring of the tire by the slight and simultaneous 

 insertion or penetration of the nutted ends of the spokes to the interior surface 

 of those cells. 



The strength of the patent wheel is in proportion to the power of the 

 rods forming the spokes to suspend a weight ; these spokes not only operate in 

 bearing the weight with which the wheels are loaded, but in binding and keeping 

 the whole together, each acting with its opponent in suspending the nave from the 

 rim. In common wheels, the spokes contribute little or nothing in binding the 

 parts together, which depends solely on the tire ; so that the fracture or relaxation 

 of this, whilst the wheel is in motion, would necessarily cause the separation of all 

 the parts. This disruption and consequent breaking down could not possibly take 

 place in the patent wheel, even though the rim were completelysevered bya cannon 

 shot. Such was actually the case in the experiments lately tried at Woolwich, and 

 yet the wounded wheel, which had been placed before the butt, was put on to the 

 axle of the gun, and employed to carry it out of the field, whilst the wooden oue 

 which had been struck by the shot exactly in the same manner, was left in scattered 

 fragments on the ground. The little model brought out by me sustained with 

 ease 14 cwt., and might safely be loaded with a ton, and from hence a calculation 

 may be made of the great strength of the full-sized wheels. 



After an engagement, or during an action, the patent wheel may be repaired 

 in a few minutes, in case of some of the spokes being shot away, by the introduc- 

 tion of fresh ones ; whilst in such case the common wheel would be rendered 



