STONE AND CEMENT CONSTRUCTION. 507 



4. If the cost of hauling in the U. S. is estimated at 250 millions 

 of dollars annually and we could save 150 millions by having good roads, 

 how many miles of Macadamized roads would that amount of money 

 build at $5,000 per mile? 



Farm Mechanics. 



The following problems are to illustrate the power required 

 to draw loads over different kinds of roads. 



The Missouri Experiment Station made experiments with 

 three sets of wheels of different height, the diameter of the axle 

 remaining the same. 



The net load in every instance was 2,000 pounds. 

 The tires were six inches wide. 



The three sets of wheels tested were of the following de- 

 scription : 



Height of Height of 



Front Rear 



Wheels. Wheels. 



1. Standard Wheels 44 inches 55 inches 



2. Medium Wheels 36 inches 40 inches 



3. Low Wheels 24 inches 28 inches 



The draft was determined by means of the Giddings self- 

 recording dynamometer, and a plainmeter, so that the average 

 draft was correctly determined. 



If a load of one ton were put upon a wagon to be drawn 

 upon a perfectly smooth hard level surface, it would be possible 

 to get accurate mathematical results, but loads are rarely if ever 

 drawn on such surfaces, so that it becomes necessary to make 

 tests of practical value. 



Such tests the experiment station has attempted to make. 



