xii TABLE OF CONTENTS 



CHAPTER XV 

 THE FORM OF TREES AND TAPER TABLES 



PAGE 



166. Form as a Third Factor Affecting Volume 196 



167. Taper Tables, Definition and Purpose ; 197 



168. Methods of Constructing Taper Tables 197 



169. Limitations of Taper Tables 204 



CHAPTER XVI 

 FORM CLASSES AND FORM FACTORS 



170. The Need for Form Classes in Volume Tables 205 



171. Form Quotient as the Basis of Form Classes 206 



172. Resistance to Wind Pressure as the Determining Factor of Tree Form. . . . 208 



173. A General Formula for Tree Form 209 



174. Apphcability of Hoejer's Formula in Determining Tree Forms 210 



175. Form Factors 211 



176. The Derivation of Standard Breast High Form Factors 213 



177. Merchantable Form Factors 214 



178. Form Height 215 



179. Form Classes and Universal Volume Tables as Applied to Conditions in 

 America 215 



CHAPTER XVII 



FRUSTUM FORM FACTORS FOR MERCHANTABLE 

 CONTENTS IN BOARD FEET 



180. The Principle of the Frustum Form Factor 218 



181. Basis of Determining Dimensions of the Frustum 219 



182. Character and Utihty of Frustum Form Factors 219 



183. Calculation of the True Frustum Form Factor 221 



184. Calculation of the Volume of Frustums. Influence of Fixed Versus Variable 



Top Diameters 221 



185. Construction of the Volume Table from Frustum Form Factors. A Short 



Cut Method 224 



186. Other Merchantable Form Factors for Board Feet 225 



CHAPTER XVIII 

 THE MEASUREMENT OF STANDING TREES 



187. The Problem of Measuring Standing Timber for Volume 226 



188. The Measurement of Tree Diameters. Diameter Classes. Stand Tables . . 227 



189. Instruments for Measuring Diameters. Calipers, Description and Method 



of Use 227 



190. The Diameter Tape 229 



191. The Biltmore Stick 230 



192. Ocular Estimation of Tree Dimensions 234 



193. The Measurement of Heights 235 



194. Methods Based on the Similarity of Isosceles Triangles 235 



