222 FARM GRASSES OF THE UNITED STATES 



The results obtained by applying all these rules to 

 two ricks of different form are given below. 



PER CENT. OF ERROR 



First rule 14.0 17.0 



Second rule 15.6 5.2 



Third rule .7 .1 



These two ricks were measured with the utmost 

 care. It will be noticed that A is three-quarters as 

 tall as wide ; it was also quite round. B is as tall as 

 wide, and narrow topped a very common form. The 

 rule last given is seen to give very accurate results in 

 both cases, while the other two give values much too 

 small. In both cases the New Mexico rule gives large 

 errors, the error being in favor of the buyer. The 

 second rule gives a value much too small in the case 

 of the low, round rick, but is more nearly corect for 

 the tall, sharp-topped one. 



No satisfactory rule for finding the volume of a 

 round stack has yet been published, and the writer has 

 not had time to develop one in his own investigations. 

 The volume of such a stack may be found in the fol- 

 lowing manner, which, however, is too tedious to be 

 practicable: Measure the circumference of the stack at 

 each foot of its hight. Square each of the numbers 



