338 



FORESTRY AND IRRIGATION 



July 



gutters 



when the cups are 



ing the 

 dipped. 



Zinc nails. The cup and gutter sys- 

 tem has been most favorable received 

 by the owners of mills where the tim- 

 ber is sawed after it has been turpen- 



Fig. 2. Making the second half of a face 



tined. The only objection they make 

 is to the use of iron nails for hanging 

 the cups. To meet this objection zinc 

 nails are now manufactured for use 

 with the cups. Experiments have 

 shown that if such a nail is left in the 

 tree no damage whatever is done to a 

 saw that strikes it, because the metal 

 is so soft. 



ERRORS MADE IN USING THE CUP AND 

 GUTTER SYSTEM. 



Gutters. In making the incisions 

 for the gutters the eye of the broadax 

 is frequently turned down too much. 

 The outer half of a gutter inserted in 

 angle to the trunk of the tree, and 

 hence forms a shelf rather than a 

 trough (fig. 5, B). From such a gut- 

 ter the resin frequently runs off along 

 the outer edge. Furthermore, such a 

 gutter is easily forced out when the 

 dipper is removing the "scrape" from 

 such an incision lies almost at a right 

 it, the pressure of the dip knife being 



almost in line with the direction of the 

 cut. A gutter inserted carefully into 

 a properly made incision will never fall 

 out (fig. 5, A.) 



Xails. Two mistakes are frequent- 

 ly made in driving the nail on which 

 the cup hangs. First, the nail is driv- 

 en horizontally. In the latter part of 

 the season, when hardened resin col- 

 lects under the head of the nails, a 

 cup hung on it will easily drop off. 

 The head of the nail should have a 

 steep slant upward. A cup hung on 

 a nail so driven fits snugly between 

 the nail and the tree, is secure, and 

 cannot swing away from the spout of 

 the lower gutter, though it may be 

 easily removed by the dipper. Sec- 

 ond, the nail is often driven into the 

 tree above the lower end of the lower 

 gutter. A cup hung on such a nail is 

 never vertical, and its capacity is there- 

 fore diminished. Further, when a 

 cup so hung fills with water or resin 

 the increased weight tends to bring it 

 to a vertical position, thereby pressing 

 on the lower gutter and causing the 

 latter to be prized out of the incision. 

 The nail should always be driven into 

 the tree at a point slightly lower than 



/' 



Fig. 3. Making incisions for the gutters 



the lower end of the lower gutter (fig. 



4-) 



C ///>.<?. Experience has demonstrat- 

 ed that the cups will be broken if wa- 



