554 ON DRAUGHT. 



Narrow wheels, therefore, running in the same track, without doubt offer the 

 least resistance, provided there is surface sufficient to bear the weight, without 

 destruction to the foundation of the road. 



Six inches in breadth of the flat or cylindrical part, a 6, fig. 36, independent 

 of the rounded edges, will be quite sufficient, in a wheel of ordinary 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, the breadth should be pro- 

 portionably increased or diminished. 



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 ordinary 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 we 

 think they would then form a strong, durable, and economical wheel. There 

 might be some danger from the effects of wet or damp remaining in the cast-iron 

 sockets, and attacking the wood ; but we should think a small hole bored into 

 the socket to allow the moisture to escape, and common precaution in painting 

 these parts, would prevent any evil consequences. 



With respect to the size of wheels, we have shown that wheels of large 

 diameter certainly offer less resistance than small ones ; but expense and weight 

 cause a limit to this. From 4 ft. 9 in. to 5 ft. 6 in. is a good size for cart- 

 wheels, and is about the limit where any great increase of diameter would cause 

 more inconvenience and expense than would be compensated for by any advan- 

 tage gained ; and if much less in diameter than this, the draught is unnecessarily 

 augmented. 



Yet the front wheels of a waggon are always below this standard ; rarely 

 exceeding four feet, and frequently much less. This is a serious evil attending 

 the use of four wheels ; it is an arrangement originally made for the purpose of 

 enabling the front wheels to lock under the body of the waggon, which may thus 

 turn in a small space. 



Now it rarely happens that a waggon is required to turn short round, and it 

 cannot cause any serious inconvenience if it be rendered altogether incapable of 

 doing so. 



In this respect a great improvement has taken place within a few years. In 

 the place of those moving mountains which were formerly dragged slowly along 

 upon immensely heavy and broad, but low, wheels, we now see, particularly 

 on the roads leading northward from London, a great number of light, well- 

 built waggons, with much larger wheels, especially the front wheels, which, 

 instead of being small enough to turn under the floor of the waggon, are about 

 four feet six inches in diameter. As those waggons are used principally on 

 the road, and are never required to turn in a small compass, but a very small 

 action is allowed to the fore axle, and the floor and body of the waggon is con- 

 tinued from end to end of nearly the same width. 



A waggon with part of the floor and body cut away, so as to form a sort of 

 recess for the front wheels to turn into, allows of considerable movement ; and 

 by this arrangement there is nothing to prevent the front wheel being made ot 

 large diameter, as in the case just described. Our present object, however, i3 

 not to enter into a detailed description of how we should build a waggon, but 

 simply to recommend the use of large front wheels, as tending much to diminish 

 the draught. An intelligent wheelwright will always know how#o construct a 

 waggon' so as to admit of this. 



