. Forest mensuration. FiQ. 51.—TheChristen Fig. 52.—Method of application of the Christen hypsometer. THE TECHNIQUE OF MEASURING HEIGHTS 245 This same method was used to determine the value of dc for a 25-, 30-, 35-,40-foot tree, etc., up to 150 feet, and the proper graduations made on the scale is somewhat more easily read when a notch is made at each graduation. The instrument is light and compact, and with practice can be used very rapidly,provided one has an assistant to manage the 10-foot pole. It requires no measure-ment of distance from the tree, and the height i
. Forest mensuration. FiQ. 51.—TheChristen Fig. 52.—Method of application of the Christen hypsometer. THE TECHNIQUE OF MEASURING HEIGHTS 245 This same method was used to determine the value of dc for a 25-, 30-, 35-,40-foot tree, etc., up to 150 feet, and the proper graduations made on the scale is somewhat more easily read when a notch is made at each graduation. The instrument is light and compact, and with practice can be used very rapidly,provided one has an assistant to manage the 10-foot pole. It requires no measure-ment of distance from the tree, and the height is obtained by one is more rapid than either the Faustmann or Weise instrument. Its disadvantages are that it requires a very steady and practiced hand to secureaccuracy, that it cannot be used accurately for tall trees, and that it is not adaptedfor steady work because it is extremely tiresome to hold the arm in the positionrequired. This last objection may be overcome by using a staff to support thehand. 199. The Technique of Measurin
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