In many cases it is easier to roll a thing than it is to drag it. This fact led to another step in the development of the carriage; it led from the cart without wheels to a cart with a wheel--a most important step in the history of inventions. The first wheeled cart was simply a log from each end of which projected an axle (Fig. 5). The axle fitted in the holes of a frame upon which the body of the cart was placed and to which the horse or the ox was attached. As the cart moved along, wheel (log and axle) turned together. The very ancient method of moving a load by rolling it along was in use in the United States not so very long ago. As late as 1860 in some of the southern States hogsheads of tobacco (Fig. 6) were rolled over country roads in the manner just described and as late as 1880 the fishermen of Nantucket used as a fish cart a vehicle that had only a barrel for its wheel. (Fig. 7.) The common wheel-barrow and the one-wheeled carts which are still used in China and Japan had their origin in the rolling log. [Illustration: FIG. 5.--THE FIRST CART. FIG. 6.--HAULING TOBACCO. (From a Model in National Museum.)] [Illustration: FIG. 7.--A NANTUCKET FISH CART. (From a Model in the National Museum.)] We are told by some writers that the rolling log (the one-wheeled cart) was followed by the two-wheeled cart, on which the wheels were the ends of a log and the axle was the middle portion of the log hewn down to a proper size (Fig. 8). Here wheels and axle turned together precisely like a modern car wheel. This makes a very pretty story but I am afraid the solid two-wheeled affair represented in Figure 8 is only imaginary, and that in a true account of the development of the cart it has no place. The true beginning of the two-wheeled cart may be learned from Figure 9. Here the wheels are two _very short_ logs through the center of which are holes in which the round ends (axles) of a piece of timber (the axle-tree) fit. When the cart moves, the wheels turn upon the axle. The one-wheeled cart had at first _one log_ turning _with_ the axle; the two-wheeled cart at first had as its wheels two very short logs turning _on_ the axles. [Illustration: FIG. 8.--A CART WITH WHEELS AND AXLE IN ONE PIECE.] [Illustration: FIG. 9.--CART WITH A SOLID WHEEL.] [Illustration: FIG. 10.--CART WITH WHEEL PARTLY SOLID. (From a Model in the National Museum.)]