504 



WHE 



WHE 



into the naves, that the wheels 

 gather at the bottom. This evi- 

 dently gives an advantage to the 

 axle ; as the wood, in fitting it to 

 the holes of the naves, is not cut 

 across the grain on the under side, 

 it is not so liable to be br* ken by 

 the weight of the load. Whether 

 there be any other advantage in it, 

 I do not deternfiuie. But it is cer- 

 tain that, in this case, the spokes 

 in the lower part of the wheel, 

 which have the whole pressure of 

 the load, will be the nearer to a per- 

 pendicular situation, while on level 

 ground, which seems to be some 

 advantage. But the lower spokes 

 ought in no part of a sidling road 

 to lean outwards. For this will 

 put both the axle and the wheel to 

 a great strain. 



5. Hi^h wheels are more easily 

 drawn than low ones. They have 

 less resistance from friction, sup 

 posing the axle to be of the same 

 size as in low wheels, which ought 

 to be supposed, the load being the 

 same. For a wheel that has dou- 

 ble the circumference of another, 

 will make but one turn while the 

 other makes two ; consequently the 

 first will have but half so much 

 friction to overcome as the second. 

 High wheels have also the advan- 

 tage of low ones in surmounting 

 obstacles, as every spoke acts as a 

 lever, in moving the wheel for 

 ward, and as a longer spoke re- 

 moves the power to a greater dis- 

 tance from the weight. And high 

 wheels easily pass over holes into 

 which small ones would sink; and 

 the impression they make upon soft 

 ground is not so deep as that which 

 is made by small ones, as a greater 



' portion of their rim is always in 

 contact with the soil. 



It is objected, that a cart with 

 high wheels is more apt to over- 

 turn. This inconvenience might 

 be easily removed, by fastening the 

 lower timbers of the cart to the 

 under side of the axle, as in some 

 parts of this country has been prac- 

 tised for a long time, particularly 

 in coal carts. 



Another objection to high wheels 

 is, that they make the cattle draw 

 too high. This may receive the 

 same answer as the former. Or 

 they may be made to draw low, by 

 fixing the traces to arms made for 

 the purpose, reaching as far below 

 the axle as any one pleases. 



6. The fore and hinder wheels 

 of a waggon should be of equal 

 height, in order to render the 

 draught as easy as possible, as Dr. 

 Desaguliers proved by experi- 

 ments. 



7. All persons who use the same 

 roads should place their wheels at 

 the same distances from each other. 

 For he who does not observe this 

 caution, but makes them go two or 

 three inches wider or narrower, 

 will find that he must carry a less 

 load than others do, in proportion 

 to the strength of his team. 



Lastly, broader rims than those 

 which are in common use, would 

 be more conducive to the goodness 

 of the roads, if all who drive teams 

 in the same roads would agree to 

 be confined to the same breadth. 

 For the broader the rim, the less 

 the wheels will sink into the soil ; 

 but the narrower the rim, the 

 deeper ruts will be made. See 

 the article Cart, 



