In addition to log rules based on board feet we have in use 

 in northern Massachusetts, and also to some extent in south- 

 ern Massachusetts, the so-called caliper cord. The basis of 

 this rule is the cylindrical foot, a cylinder a foot in diameter 

 and a foot in length. It will be seen that by placing four of 

 these end to end one has a stick 4 feet long and 1 foot in 

 diameter. Eight such sticks placed side by side and four 

 ranks deep will occupy a space 8 feet by 4 feet by 4 feet, or a 

 cord, hence 128 cylindrical feet equal a cord. By means of 

 a special caliper measure used on the middle of the log the 

 number of cylindrical feet in that log are determined, and 

 128 such feet are called a cord. 



There is a variation of this caliper cord rule very consider- 

 ably used, called the Humphrey rule, in which the cylindrical 

 foot unit is somewhat larger than 1 foot, and so proportioned 

 that 100 instead of 128 cylindrical feet will occupy 128 cubic 

 feet of space. This makes it possible to express the volumes 

 of the logs in decimal parts of a cord, and it is therefore very 

 convenient to use. The resulting sum is exactly the same 

 as the ordinary caliper cord rule. 



