ON DRAUGHT. 433 



he describes Juno's chariot. He there says, while Juno was putting the 

 golden bits to the horses, Hebe fastened on the wheels to the iron axles. 

 ' These wheels had eight brazen spokes, and the felloes were of gold, 

 and the tires of brass.' — ' The seat was fastened with gold and silver 

 cords.' 



This, of course, gives us Homer's ideas of perfection in a chariot. 



All the epithets which could convey ideas of swiftness, were applied to 

 these chariots and to the horses, but we have no positive information as 

 reo-ards the real velocity with which they would travel : as roads were 

 scarce, and probably at best merely tracks, much could not be expected 

 from vehicles constructed under such circumstances ; the wheels were 

 small, from 20 to 30 inches diameter, and all the parts of the chariots 

 excessively heavy, so as to resist the repeated shocks to which they were 

 subject. 



The chariots represented upon the Frieze of the Parthenon, before 

 alluded to, and which is probably upwards of 2200 years old, are very 

 light in their construction, and only want springs to be called gigs. 



The advancement of all the branches of the mechanical arts has ne- 

 cessarily introduced many improvements in the details of the construction 

 of the wheel itself, as well as in that of the axle and the rest of the carriage, 

 and by this means no doubt increased very greatly the use and advantage 

 of it ; but it is a remarkable fact, that these improvements have beeu con- 

 fined exclusively to the workmanship and mechanical detail, and that the 

 prmciple has remained exactly the same, and has not even received any 

 addition during this immense lapse of time. 



Upwards of 3000 years ago, the wheels appear to have been independent 

 of each other and running upon fixed axles ; we can say no more of the 

 most improved wheel of the most finished carriage of the present day. 



We are far from intending to cast any slight upon modern invention, or 

 to compare the groaning axletrees and creaking wheels of the ancients with 

 the noiseless Collinge's axles of the nineteenth century; but truth compels 

 us to acknowledge that a period of thirty centuries, more than half the 

 time which is supposed to have elapsed since the creation of the world, 

 has produced no radical change nor brought into action any new principle 

 in the use of the wheel as applied to carriages. 



The particular form and construction of the wheel, as well as of all the 

 other parts of the carriage, however, admit of great variety, and the 

 draught is materially affected by their variation. We shall, therefore, 

 after examining the action of wheels in general, describe the mode of 

 construction now adopted, and then endeavour to point out the advantages 

 and disadvantages of the various forms which have been given to the 

 different parts of it. 



First let us examine the theory of it, and suppose it acting on a level 

 plain. 



The wheel being a circle, the centre will remain always at the same height, 

 and consequently will move parallel to the plane in a perfectly level line : if 

 any weight be attached to or suspended from its centre, this will also move 

 in a continued straight line without rising or falling, and consequently 

 when once put in movement, there is nothing to check its progress (neg- 

 lecting for the moment the slight resistance of the air), and it will require 

 no force to keep it in motion so long as the wheels continue to turn. 



We have therefore in this case only to examine into the force necessary 

 to turn the wheels. The wheels, if left to themselves, would roll on with 

 perfect freedom, whatever might be their weight, or whatever weight might 

 be attached to them, provided nothing in theanode of attaching that weight 



2F 



