84 PARA RUBBER. 



It will thus be seen that the employment of this method 

 likewise considerably reduces the work in connection with 

 collecting cups as compared with the V method. 



Spiral incisions were much in vogue a few years ago, and 

 enormous yields were obtained, but this was, in the majority of 

 instances, at the expense of a disproportionate amount of bark. 



On several estates the whole of the bark up to a height of 6 

 feet from the ground was pared away in one season. Such 

 rapid excision of the cortex can only be regarded as pernicious 

 to the tree's vitality and must adversely affect its future yield. 

 Assuming that trees seven years old be tapped for the first 

 time by this method, bark which has taken seven years to 

 develop is demolished in one year, and it is unlikely that the 

 new one-year-old bark will be as productive as that which it 

 replaced. Such rapid excision is not by any means essential 

 when spiral tapping is adopted, as the original bark on some 

 estates, where this method is employed, is estimated to last for 

 three years. 



To ensure the incisions being made at the proper distances 

 apart, and at the necessary angle, the positions for the initial 

 incisions should be marked. Cut a piece of tin or similar 

 substance in the form of a right-angled isosceles triangle, the 

 side subtending the right angle being 2 feet long and the two 

 equilateral sides 17 inches long. 



This guide should be pressed flat against the trunk at the 

 height it is intended to commence operations, one of the 

 equilateral sides being at right angles to the trunk, the line for 

 incision being marked along the hypotenuse. By carefully 

 removing and adjusting the guide, this line may be continued to 

 the base of the tree. The line for the second incision may then 

 be marked by placing the apex of the right angle of the guide at 

 the origin of the first line, one equilateral side being parallel 

 with the trunk and the other uppermost ; the hypotenuse then 

 indicates the correct direction for the second incision, which may 

 be marked as suggested with regard to the first one. It will be 

 now patent that a tree under 34 inches in circumference, at the 

 height from the ground above which it is not proposed to tap, 

 will only have one spiral incision, or in other words, one spiral 

 incision may be made for each 17 inches of circumference at the 

 height indicated. 



