CIRCLES. 297 



EULE 2. Or, multiply half the circumference by half 

 the diameter. 



RULE 3. Or, as 14 is to 11, so is the square of the diam- 

 eter to the area. 



RULC 4. Or, as 88 is to 7, so is the square of the circum- 

 ference to the area. 



To find the side of an equal square containing the same 

 area as a given circle. 



RULE. Take the square root of the area, which will be 

 the side of the equal square. 



To find the solidity of a sphere. 



RULE. Multiply the cube of the diameter by .5236, and 

 the product is the solidity. 



EXPLANATION AND USE OF THE FOLLOWING TABLE. 



In the left hand column will be found the diameter of the 

 circle; in the next column to the right will be found its 

 corresponding circumference ; in the third to the right will 

 be found the area, and in the right hand column will be 

 found the length of the side of an equal square containing 



the same area. 



* 



EXAMPLE. What is the side of a square having the same 

 area as a circle of 64J inches diameter ? 



SOLUTION. Find 64 in the left-hand column, and oppo- 

 site it to the right, under the heading " Side of Equal 



Square," will be found 57.101, the length of the side. Ana. 



13* 



