CONTENTS. IX 



CHAPTER V. 



APPLICATION OF MECHANICAL PRINCIPLES IN THE STRUCTURE OF THE 

 PARTS OF IMPLEMENTS AND MACHINES Page 96 



CHAPTER VI. 



FRICTION. 



SECTION L 



Rolling Friction 103 



Nature of Friction 104 



Estimating the Amount of Friction 104 



SECTION II. 



Results with the Dynamometer 107 



Width of WTieels 109 



Velocity as affecting Friction 110 



Friction at the Axle Ill 



Friction Wheels 112 



SECTION III. 



Lubricating Substances 113 



Advantages of Friction 115 



SECTION IV. 



Principles of Draught 117 



Combined Draught of Animals 120 



SECTION V. 



Construction and use of the Dynamometer 122 



Self-recording Dynamometer 125 



Dynamometer for Rotary Motion 126 



CHAPTER Vn. 



CONSTRUCTION AND USE OF FARM IMPLEMENTS AND MACHINES. 



SECTION I. 



Plows and Plowing 130 



Trench and Subsoil Plowing 134 



The double Mould-board Trench Plow 135 



The Subsoil Plow 136 



Fowler's Draining Plow 136 



The Paring Plow— The Gang Plow 140 



A2 



