To come more directly to our subject of the wheel, Lynn 
White explains how the evolution of the wheel in the Middle 
Ages was related to the development of the horsecollar and the 
harness. The greater speed and endurance of the horse was 
not available for cartage until the discovery of the collar. But 
once evolved, this horse-harness led to the development of 
wagons with pivoted front axles and brakes. The four-wheel 
wagon capable of hauling heavy loads was a common feature 
by the middle of the thirteenth century. The effects on town life 
were extraordinary. Peasants began to live in cities while going 
each day to their fields, almost in the manner of motorized 
Saskatchewan farmers. These latter live mainly in the city, 
having no housing in the country beyond sheds for their 
tractors and equipment.

     With the coming of the horse-drawn bus and streetcar,