THE GRAPHIC COMPARISON OF LOG RULES 19 



4. From these curves read off the vohimes for the missing lengths, and 



enter in the table. 



5. Take a smooth stick-0.5XlXl3 inches and enter on it the values in 



the table, in the same manner as they occur on the ordinary scale 

 stick. 



B. References. Numbers 17, 18, 25, 26, and 27. 



C. Discussion. 



1. Write brief directions for using the scale stick in scaling logs. 



2. What is the object in drawing the curve in this problem? 



3. What particular fundamental principles make the International Rule 



more accurate than other formula rules such as the Doyle. 



4. What advantages has a formula rule over a diagram rule? 



PROBLEM 10. (Office.) The Graphic Comparison of Log Rules. 



Explanation. — To illustrate the extreme variations in values obtained by 



scaling with different log rules. 

 Illustration. — The International, Scribner, and Doyle Rules. 



Directions : 



A. Method of Procedure. 



1. On a sheet of co-ordinate paper lay off diameters in inches as abscissa 



on the long edge of the sheet, and volumes in board feet as ordinates. 

 Be sure first to determine the number of spaces you will allow to 

 each unit by an examination of the data to be plotted. 



2. With values read from a scale stick, or from the respective tables in 



Graves' Mensuration or the Woodsman's Handbook, Bull. 36 U. S. 

 Dept. of Agr., construct on the same sheet of cross-section paper 

 curves representing the values of the 16-foot logs of all diameters 

 given by the International, the Scribner, and the Doyle Rules. 



B. References. Numbers 16, 19, 20, 23 and 24. 



C. Discussion. 



1. Comment on the relationships as illustrated by the curves. 



2. Could a combination table for the " Doyle-Scribner " Rule be con- 



structed so as to yield low values? 



PROBLEM 11. (Office.) The Extension of Log Rules. 



Explanation. — The object of this problem is to show how log rules with values 

 reading only to a certain point may be extended so that the rule may be 

 applied to logs of other dimensions. The method of procedure here outlined 

 for log rules may also be used in the extension of volume, growth, or any other 



