166 FIRST BOOK OF FORESTRY 



inches in diameter at the top end ; the second is seventeen 

 inches at the top, and the third fifteen inches at the top. 

 Looking in our table (Appendix I), we find that by the 

 Doyle rule these logs contain, 



The first one 225 feet B.M. 



The second one 169 feet B.M. 



The third one 121 feet B.M. 



Total, 515 feet B.M. 



which means that five hundred and fifteen feet B.M. of 

 boards may be cut from the logs of this tree, provided 

 the logs are straight and sound. Usually this is not quite 

 the case, and ten to thirty per cent, according to the 

 quality of timber, must be deducted for " defects." 



After some practice in a forest the estimator or cruiser 

 commonly decides that the trees generally cut one and a 

 half, two, or three logs per tree, and also that it takes 

 about eight, twelve, or twenty of these logs to make a 

 thousand feet B.M. 



Thus, in ordinary eastern spruce, the trees cut about 

 three logs per tree and it takes about fifteen to twenty 

 logs to make a thousand feet B.M., so that the estimator 

 finally decides that about five trees make a thousand feet 

 B.M. After this he merely counts the trees and divides 

 by five, to find how many thousand feet B.M. he has esti- 

 mated. In old white pine he would find that it takes 

 about two trees to make a thousand feet B.M. (write M 

 feet B.M.), and in large red fir and redwoods one tree often 

 would make five to ten M feet B.M., and even more. 



