168 



FARM ARITHMETIC. 



crease does not depend upon the amount of draft on the 

 level, but only upon the total weight of the load and the 

 slope of the grade. The slope of a grade is the ratio of 

 the rise to the horizontal distance. A rise of 2 feet in 

 40 feet gives a slope of one-twentieth or a grade of 1 to 20. 



594, What is the grade or slope of a hill having a rise 

 of 3 feet in 90 feet? Six inches in 8 feet? 



I-ATTENING STEERS. 



595. How much rise in going % mile up a slope of 2 

 to 50? How much fall in going down such a slope a dis- 

 tance of 300 feet ? 



A grade is frequently expressed as a per cent instead 

 of as a ratio. The per cent of a grade is the per cent 

 of the rise as compared with the horizontal distance. 

 A rise of 2 feet in 50 feet. i. e., of 4 feet in a hundred 

 feet, is called a 4 per cent grade; 7^^ feet in a hundred 

 would he aiy2 per cent grade. A grade may also be ex- 

 pressed in degrees — i. e., the angle it makes with the hori- 

 zontal. 



