Wheels which were made before the introduction of iron were of course very clumsy in their construction, in order to obtain the requisite strength. Specimens may still be seen in the broad wheels of waggons, technically termed rollers. The naves of these wheels are of enormous size. But when the naves of wheels were reduced for the purposes of elegance, a thin hoop of iron was applied both to the front and back, to prevent them from bursting by the strain on the spokes. When the felloes of wheels were reduced in size, straps of iron, called strakes or streaks, were applied to their convex surfaces covering the joints. But the last improvement was the most important of all, namely, the application of a “hoop-tire” instead of what was called the “strake-tire.” Mr. Felton, in his treatise on coach-building, 1709, says, “Many persons prefer the common sort of wheel on account of their being more easily repaired than the hoop-tyre wheel; but though repairing the latter is more difficult, they are much less subject to need it.” The earliest form of wheel was no doubt a slice of the trunk of a tree; portions of this being cut out for the purpose of lightening it would be the forerunner of spokes, or we should think the pieces left running from the nave to the felloe would be. The only improvement then effected for a very long period was making them of different pieces of timber instead of all from one piece, though of course the proportions of the parts would be considerably improved, if only for the sake of appearance. At the end of the seventeenth century, among the wealthier classes, decoration was applied to coaches generally, and wheels in particular, to an extent which would surprise us nowadays. These latter were again ornamented as in the times of the old Roman Empire; the spokes were shaped and carved, the rim moulded, and the naves highly embossed; though, as may be imagined, there was a great want of taste in the application of all this ornament. Towards the end of the eighteenth century, the extreme height of wheels extended to 5 feet 8 inches, which had but 14 spokes; wheels 5 feet 4 inches high had 12 spokes; wheels 4 feet 6 inches had 10 spokes; and the lowest wheels, 3 feet 2 inches high, had 8 spokes. The naves were of elm, the spokes of oak, and the rims or felloes of ash or beech. The rims of the higher wheels were often of bent timber, in two or more pieces, and were bolted to the tires by one bolt between each pair of spokes. The tire was put on in pieces, until the hoop-tire came into general use, when it superseded the old ones entirely. In consequence of the great height of the wheels it was necessary to make the carriages very long, and the distance from the front to the hind axletree was 9 feet 2 inches in a chariot, and 9 feet 8 inches in a coach, or about 8 inches longer than we should consider necessary now.