THE IRRIGATION AGE. 



47 



EVOLUTION OF THE WAGON. 



Primitive man carried his fire-wrod and prey 

 upon his back, or he dragged it along the ground 

 when it was too heavy to carry. 



The problem of better facilities for transporta- 

 tion was before him always. It confronted him 

 when he was cold and when he was hungry. 



The first attempt at solving this problem of 

 transportation was probably to use his wife's back 

 instead of his own for carrying his burdens. . His 

 wife, however, could not carry all he wished, so he 

 pressed animals into his service to carry and drag 

 his burdens. 



Sledge. 



In time, by the slow process of evolution, the 

 sledge appeared. The sliding friction of the smooth 

 sledge was less than the friction caused by dragging 

 the burden directly along the ground. The energy 

 this required to overcome was less than the energy 

 required to overcome the weight of the burden by 

 lifting it bodily and carrying it. Attaching animals 

 to the sledge in place of his wife, or to help his 

 wife, naturally followed. 



A crude form of sledge, but fully embodying 

 its principles, was used by the North American 

 Indian. He attached a pole to each side of his 

 pony with the ends of the poles trailing along the 

 ground behind. Across these poles or runners the 

 load was fastened. 



Roller. 



Evolution in transportation next gave us the 

 roller which substituted rolling friction for the slid- 

 ing friction of the sledge. 



Tke great advantage of the roller is exhibited 

 in the transportation of heavy bodies such as enor- 

 mous blocks of stone as used in the construction of 

 the pyramids. Ancient Egyptian pictures show 

 sledges mounted on rollers. 



As a means of ordinary transportation in which 

 the element of time is important, the roller had one 

 very objectionable feature. As the load moved for- 

 ward, drawn by man or other power, the roller was 

 left behind, and it was necessary to constantly place 

 rollers under the front portion of the load or frame- 

 work on which the load rested. To overcome this 

 objection, rollers were permanently attached to the 

 sledge or framework that carried the load. 

 Oxcart. 



The reduction of the diameter of the roller, 

 except at the ends, gave us the axle with wheels 

 at either end, in principle the same as our axles and 

 wheels on railroad cars. A later development was 

 to attach the axle rigidly to the framework and 

 fasten the wheels to the ends of the axle in such 

 a manner that they could revolve. 



This gave us the solid wheel which is still in 

 existence on the old Mexican ox-cart in some of the 

 remote regions of Mexico. 



The next problem was to lighten the wheel and 

 at the same time strengthen it, from which resulted 

 the modern wagon wheel. 



Wagon. 



How man}- centuries or hundreds of centuries 

 it took to evolve the sledge, the roller, and finally, 



the wagon, is impossible to say, but it is certain 

 that the most ancient people of whom we have any 

 knowledge were in possession of the wagon. The 

 ordinary wagon in use today is the same in prin- 

 ciple as the wagon used by the Greeks and the 

 Romans and the people who preceded them. 



Details of construction have been improved, 

 better materials used, but the underlying principles 

 remain the same, that is, the rolling friction of the 

 wheel on the ground and the sliding friction of the 

 wheel on the axle. 



The fact that a rolling friction is preferable to 

 a sliding friction shows itself in that the roller fol- 

 lowed the sledge. 



Great improvements have been made in the 

 direction of reducing the rolling friction on the 

 ground by building better roads. 



Smoother surfaces and better lubricants for the 

 bearings at the axle, and, finally, the introduction 

 of the roller bearing have greatly reduced the slid- 

 ing friction of the wheels in the hubs. 



Roller bearings do away with the sliding fric- 

 tion in the hub and gives us the rolling friction. 

 They have been applied with marked success on 

 line shafting, on the axles of automobiles, and some 

 agricultural implements like wagons, harvesters, 

 mowers and manure spreaders. 



The principle only requires the placing of roll- 

 ers between the axle bearing and the hub bearing. 

 As the wagon moves forward, there is no sliding 

 friction of the axle bearing against the hub bearing, 

 but instead the rolling friction of the rollers against 

 these bearings. 



Davenport Roller Bearing Steel Wagon. 



Davenport Roller Bearing Steel Wagons are 

 built entirely of steel. The only equipment that 

 will stand the climate of the irrigated districts is 

 made of steel. You know the reason wood dries 

 out, becomes useless and the machinery falls apart. 



Davenport Roller Bearing Steel Wagons are 



Davenport Roller Bearing Steel Wagon. 



stronger, lighter draft and more durable. Each one 

 will outlast several wooden ones. 



They are built of I-beams, channels and angles 

 riveted together with steel rivets put in while hot, 

 making practically one solid piece. There are no 

 bolts to become loose and no nuts to rattle off on 

 account of parts shrinking and drying out. 



Makes no difference what the climate is, it does 



not affect Davenport wheels. They are made with 



a tension, each spoke carrying its share of the load 



all of the time whether it is on the top, bottom or 



(Continued on Page 54.) 



