ON DRAUGHT. 441 



wheels, and nine-inch wheels seven inches outside, tjey are then called 

 straddlers, and are allowed to carry a greater weight than if not so. The 

 original intent of these was most excellent ; but the effect has been defeateQ 

 Dy the carrier or other person not only making the bed or axle contrary tc 

 what was intended, but also by carrying with them a false collar, with a 

 joint therein, to put on and take off at pleasure ; so that they have no great 

 difficulty in making the wheels straddlers a little while before they como 

 to a weighing machine, and making them not so when they have passed 

 the same." 



On modern roads such an arrangement would hardly be beneficial even 

 to the road itself, and would nearly double the amount of draught. 



Too great care and precaution cannot be taken to insure the wheels run- 

 ning in'the same track. Let it be remembered that, on a good road, the 

 forming the rut is the cause of three-fourths and oftener five-sixths of the 

 whole resistance. Narrow wheels, therefore, running in the same track, 

 without doubt offer the least resistance, provided there is surface sufficient 

 to sustain the weight borne upon them, without material destruction to the 

 foundation of the road. 



Six inches in breadth of the flat or cylindrical part, a, b, fig. 3G, inde- 

 pendent of the rounded edges, will be quite sufficient, in a wlieel of ordi. 

 nary size, to bear a ton without injury to the roads, if in good condition ; 

 and"^according as the weight upon each wheel is more or less than this, tho 

 breadth should be proportionably increased or diminished. 



While upon the subject of wheels, it may be as well to state the several 

 new modes of constructing wheels lately introduced, which severally pos- 

 sess their merits and disadvantages. The last improvement is that known, 

 under the name of "Jones's patent wheels." 



It consists in making the felloe of a single ring of cast iron. The nave, 

 which is also of cast iron, is suspended in the centre by eight wrought iron 

 rods : these rods are crossed or alternately dished inwards and outwards, 

 to give stiffness, which is thus obtained without affecting the cylindrical 

 form of the whole. 



Figs. 37 and 33 (see next page) represent different views of this wheel, 

 F F being the cast iron felloe, S S the spokes, and N the nave. 



These wheels have been adopted to a very great extent in London, and 

 therefore, we may conclude that they are found to answer; but they are 

 expensive, and not easily repaired, except at the original manufactory, and 

 therefore we should think are not so well adapted tor agricultural, as for 

 commercial purposes, and in a large town where the means of repair may 

 be at hand. 



The most simple innovation upon the original wooden wheel is the cast 

 iron nave. This we should think, must be much less liable to wear than 

 the wooden nave, which is literally honeycombed with the mortices for 

 the spokes ; and a wheel of this sort can be repaired by the most ordi- 

 nary wheelwright, provided he has one of the castings at hand. 



We should strongly recommend that these naves should be made with 

 a double row of sockets for the spokes, so as to cross the dishing of them 

 in the same manner as those of the wrought iron wheels described above : 

 and vve think they would then form a strong, durable, and economical 

 wheel. There might be some danger from the effects of wet or damp 

 rejnaining in the cast iron soclcets, and attacking the wood ; but we shoula 

 think a small hole bored into the socket to allow the moisture to escape, 

 aud common precaution in painting these parts, would prevent any evil 

 ucnsequences 



Ff 



