CH. Ill WHEEL 45 



put on in pieces and secured by bolts ; they over- 

 lapped the joints of the fellies and added to the 

 strength of the wheel, but not nearly so much as 

 does the modern hoop-tire, which is continuous and 

 binds the wheel tightly together. The hoop-tire is 

 made somewhat too small to oo on the wheel ; it is 

 expanded by heating, and being then put on the 

 wheel, is rapidly cooled and shrunk by the applica- 

 tion of water. A great deal of judgement must be 

 exercised by the smith in this operation with light 

 wheels, as they may have their dish increased be- 

 yond the intention of the designer, by drawing the 

 tire too tight. Machines are now made which com- 

 press the tire after it is on the wheel without its 

 having been previously heated. 



According to Corbett, p. 28, continuous tires 

 were adopted for the coaches before they were used 

 on the mails. On some of the wide wheels of the 

 old 'stage-waggons,' two widths of strokes were put 

 on with their joints overlapping. 



There are many details of the construction of 

 wheels too technical to be entered upon here, but 

 it may be said that there is no good reason for 

 making the tire very narrow on upright wheels, es- 

 pecially as a somewhat wide tire protects the rim 

 of the wheel, which is otherwise liable to be rubbed 

 and scratched. If it projects too much beyond the 

 rim it will cast up the mud. There is no advan- 

 tage in a narrow or round faced tire on a vertical 

 wheel, but on a coned wheel there is an advantage, 



