BICYCLES AND TKICYCLES. 



is stretched about the rim and fastened for 

 greater security with a kind of cement made 

 for the purpose. 



THE KANGAROO. 



The rim or felloe of the wheel is either U- or 

 V- or crescent-shaped in section, the groove 

 being designed to hold the tire. 



The spokes are of either charcoal-iron or 



THE 'XTRAORDINART. 



steel wire, and are headed at the rim, from 

 which they pass alternately to either side of the 

 hub, where they are fastened to the flanges in 

 one of two ways : 1. Uy nipples, which are pieces 



of steel about one inch long, having a screw 

 cut on one end, the other taking the form of a 

 nut ; through the center of this, longitudinally, a 

 hole is drilled, the spoke is passed through and 

 headed, and the nipple is then screwed into 

 the hub. 2. By screwing the spokes themselves 

 directly into the hub. 



The hub consists of the axle and the flanges; 

 these latter are circular disks of metal about 

 four inches in diameter in the fore-wheel, and 

 smaller in the rear-wheel ; they are firmly se- 

 cured to the ends of the axle, and to them the 

 fepokes are fastened. 



These parts constitute the snspension-wheel, 

 the theory of which is, that the rim should be 

 a perfect circle and true in its own plane, with- 

 out reference to the spokes ; then these latter 

 suspend the weight at the hub from the rim, 

 and the pull of the spokes all around preserves 

 the circular shape of the wheel. 



The bearings are of three kinds parallel, 

 cone, and ball. Parallel bearings are con- 

 structed with a plain axle or spindle, fitted 

 with a plain hardened steel cylinder. Cone 

 bearings are of two kinds: with the ends of 

 the axle in the form of a hollow truncated 

 cone, and the bearings beveled at their edges 

 to fit them; or with the bearings hollowed, 

 and cones on the axle to fit. Ball bearings 

 consist of either a single or double row of balls, 

 introduced between the axle and the bearing- 

 case, substituting a rolling for a sliding fric- 

 tion; these balls are either in a groove con- 

 tinuous around the bearing, or in separate cir- 

 cular holes. 



The fork connects the bearings of the front- 

 wheel with the head and backbone, for which 

 it furnishes support, and by it, through the 

 head and handles, the front-wheel is guided 

 and held against obstructions tending to deflect 

 it from its course. It also takes the vertical 

 lift and thrust of the rider when he adds 

 strength to his weight for propulsion, and 

 so must combine with lightness rigidity 

 against forward, backward, lateral, and ver- 

 tical strain, and the twist of turning the 

 handles. It is usually constructed of flat- 

 tened steel tubing, tapering gradually from 

 the head to the bearings. 



The head is that part above the fork 

 which affords bearing and connections for 

 the perch and the handles. 



The perch serves to connect the other 

 parts of the machine, and is subject to 

 much strain. It is a round or elliptical steel 

 tube, tapering from a point below the saddle 

 downward to the point of bifurcation for the 

 rear- wheel. 



The saddle is small and nearly heart- 

 shaped, with the small end foremost, and 

 consists of a light, strong frame, over which 

 a piece of leather is stretched taut. It is 

 attached to the spring, which in turn is fastened 

 to the perch immediately behind the head. 



The accessories are a small oblong bag for 

 carrying an oil-can, a wrench, and other tools; 



