V. INSTRUMENTS AND TECHNIQUE 



In dealing with the 175,000 growth-rings, dated, measured, and 

 used in these volumes, special tools have been adopted or developed 

 at every stage of the process to secure material and to hasten and 

 improve results. 



COLLECTING TOOLS 



Saws — The articles needed in field trips include a chisel for marking 

 numbers, paper and cloth bags for holding fragments cut from individ- 

 ual trees, a recording notebook, marking crayon, a shoulder-bag, 

 camera, and various saws and borers. The best handsaw is known 

 as a flooring saw, in which the teeth are on a curved edge of steel, 

 as shown in Plate 2, A. With this, one can make a v-cut in the middle 

 of a stump without touching the edge at all, or the saw can cut in from 

 one side to the center without touching the other half. In working 

 without help this has saved many hours of labor and energy. The 

 convenient size of saw has a blade about 20 inches long. A 3-foot 

 cross-cut saw used by lumbermen does at times prove very useful, 

 but its extra weight and awkwardness in packing have always been 

 against it. 



Swedish increment borer — Since 1920 the Swedish increment borer 

 has been used extensively to get records from living trees. It is very 

 successful in softwoods such as pine and fir. Hardwoods and juniper 

 are too tough for penetration without great danger of breaking the 

 instrument. The cores obtained are very slender, smaller than a pencil, 

 and reach to slight depth in large trees, but the method of mounting 

 has been raised to such a degree of efficiency and the collection of 

 material becomes so rapid that the deficient length and occasional 

 worthless specimens are counterbalanced. In most regions the incre- 

 ment-borer material can be supplemented by a few cuts from stumps 

 carrying the tree record back into the past as far as the forest permits. 

 Thus the borer supplies the contemporary record, that is, the last 100 

 years or so from many trees, and the saw supplies the historic record 

 going back for centuries. 



In countries where native timber has been cut off and the yearly 

 "crop" of lumber comes from planted and reforested areas, it is very 

 important to know how growth is progressing. So Swedish ingenuity 

 produced this tool for sampling the outer rings of a tree. The borer 

 is a tube of 4 to 5 mm. inside diameter (i to i inch) with a sharp 

 cutting-edge and prominent spiral threads to draw the tool into the 

 tree by twisting, as with an auger. Near the cutting-edge is the largest 

 outside diameter of the tube, about half an inch. A tubular cross- 



34 



