IROjV- work. 387 



plates and stays for new carriages, and others at 

 repairs upon old work of all kinds. The springs 

 ought to be of steel of the best quality, well worked, 

 and properly tempered, which is the chief art 

 of the spring-maker. In spring-making there is a 

 considerable nicety required in proportioning the 

 thickness and lengths of the different plates, giving 

 them an equal temper and proper set, in order to 

 produce a regularly increasing resistance to any 

 weight that may be put upon them. It is by these 

 means that a carriage can be made equally easy to 

 ride in with one person only, as with four or six. 



The axle-trees ought to be built of different bars 

 of iron, laid alongside of one another, and well 

 welded together ; for this purpose the tires which 

 come off old wheels are preferred, and the thinner 

 they are worn down, so much the better, as a greater 

 number of plies are necessary, thus receiving a better 

 mixture of metal, and, of course, greater uniformity 

 and averao^e streno^th. 



The finishing of the axle-trees ought to be done 

 with the greatest possible accuracy, as much of the ease 

 of draught depends upon that circumstance, and as the 

 greatest part of the noise made by carriages when 

 in motion, proceeds from the axle-arms and boxes 

 not having been properly fitted to one another. A 

 considerable degree of correctness is also necessary in 

 making the steps. 



The variety of iron plates and fastenings requisite 

 for a carriage is so great, that it would take too long, 

 and occupy too much space, to describe them all ; I 

 shall, therefore, merely mention that almost every piece 

 of wood in the carriage is supported by, or strengthened 

 with iron, attached to the wood-work by bolts or rivets 

 passing through both. A considerable degree of art 



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