724 JOURNAL OF FORESTRY 



lately particularly come into consideration from this point of view, as 

 the cutting for lumber and mine props threatens to interfere with the 

 naval-store industry. To meet this danger a special council has been 

 created for the two departments involved, whose advice must be sought 

 by the general commission instituted to supervise the logging for war 

 needs. 



In the southern departments the cutting of olive trees for fuel, 

 threatening curtailment of the oil industries, causes apprehension, the 

 high price for fuel stimulating this procedure. The increase of game 

 and obnoxious animals is another cause for concern and a let down of 

 restrictions on the chase, increase of premiums for destruction of wild 

 boar, etc., is advocated. 



Revue des Eaux et Forets, May, 1918. 



Mr. Donald Bruce has devised a simple instru- 

 • Nezv ment which will measure the diameter of trees at 



Dendrometer points out of reach from the ground. The evi- 

 dent practical usefulness and the requirements of 

 such an instrument are discussed. The instrument consists of a straight 

 arm upon which are mounted two small mirrors, both at an angle of 45 

 degrees with the arm, parallel to and facing each other; one mirror 

 fixed, the other sliding on the graduated arm. The direct line of sight 

 to one edge of the tree passes over the fixed mirror, while the indirect 

 line of sight is reflected in each of the two mirrors, and is secured by 

 sliding the loose mirror until the other edge of the tree is sighted and 

 its reflection is in straight line with the fixed sight. The distance be- 

 tween the two mirrors is the required diameter. 



As advantages of the instrument — not quite properly called den- 

 drometer — are stated its direct reading, its independence of distance 

 from the object, and the possibility of locating a given diameter, its 

 rapid use, its portability, light weight, and convenient shape. The ob- 

 jections are that it can measure only a moderate range of sizes, and 

 while very accurate for a hand instrument, it is not capable of extreme 

 precision. These deficiencies are explained and means for partly ove'r- 

 coming them suggested. 



Thirty inches seems the practical limit of this caliper. A modifica- 

 tion is suggested for timber-survey crews for establishing a fixed top- 

 cutting diameter. 



A Nezv DcndroDictev. University of California Publications, Vol. Ill, No. 4, 

 November, 1917, pp. 55-61. 



