256 



Our Surroundings 



and as his possessions continued to increase, it became more neces- 

 sary to have new means of transportation. Human and animal 

 pack trains helped considerably, but with the increasing need of 

 carrying food and supplies better means were required. Carts 

 were invented which could carry heavier loads. The first carts 

 were simply rough platforms rolled on logs. These were fol- 

 lowed by carts with solid wooden wheels, mere sections of tree 

 trunks, such as are still used in many outlying parts of the world. 

 The early carts were two-wheeled affairs. In fact, it took some- 

 thing like 5,000 years to develop anything like the modern wagon 

 of four wheels, with spokes and metal tires taking the place of 

 the solid wheels. 



Roads. Wheeled vehicles could not go anywhere and every- 

 where, so some form of road became necessary, and also rude 

 bridges by which to cross the larger streams. The first roads 

 were simply stretches cleared of growing trees, often with the 

 stumps left where the trees had been. They were rough and 

 rutty and often impassable. By degrees man learned to cover 

 the softer spots with brush and corduroy, logs laid side by side. 

 Finally the greater of the ancient nations built their roads of 

 great slabs of stone and some cement-like materials. Many of 

 these roads endured for ages. 



With the development of the automobile, durable roads and 

 highways have become vitally necessary. Macadam roads were 

 the first of the modern types. These are constructed of several 



inches of broken stone, over- 

 laid with thin layers of fine 

 stone and stone dust. The sur- 

 face is curved to shed water 

 and then rolled. To preserve 

 the surfaces of these roads, 

 they are oiled with com- 

 pounds of tar or of asphalt, 

 which is a natural tar-like, 

 pitchy substance. Sometimes the fine stones in the top layers 

 are thoroughly mixed with these compounds before being 

 laid. 



Brown Brothers. 



A MODERN CONCRETE ROAD 



