TABLE OF AREAS AND CIRCUMFERENCES. 101 



CIRCUMFERENCES AND AREAS OF CIRCLES. 



To find the circumference of a circle, multiply the 

 diameter by 3.1416. 



To find the area of a circle, multiply the square of the 

 diameter by 0.7854. 



To find the cubical contents of a cylinder, multiply the 

 area of the base (floor) by the height. 



Example. A silo 16 feet in diameter and 26 feet high 

 is wanted; how many staves 2x6 inches will be needed, 

 and what will be the feeding area in the silo and its 

 capacity ? 



The circumference of a circle 16 feet diameter is 50.3 

 feet; there will therefore be required '50.3-M^ 101 staves, 

 2x6 inches, 26 feet high, or if staves of this height cannot 

 be obtained, 135 staves 20 feet long, or 50 each of 12 and 

 14 feet long staves. The feeding area will be 16\16X 

 0.7854201.1 square feet, and the cubical content of the 

 silo, 201.1x26=5228.6 cubic feet. Estimating the weight 

 of a cubic foot of corn silage at 40 pounds, 5228.6 cubic 

 feet of silage would weigh 209,164 pounds, or about 100 

 tons, which is the approximate capacity of a round silo 

 of the dimensions givei*. 



