16 



WESTERN PINES AS A SOURCE OF NAVAL STORES. 



the weight of the total flow for the season from the same trees. An 

 average of the results shows that 73 per cent of the weekly flow 

 occurred in the first three days. This ratio varied from 65 per cent 

 to 78.6 per cent in the 10 test trees. 



CALIFORNIA EXPERIMENTS ON WESTERN YELLOW PINE. 



(Pinus ponder osa.) 

 DESCRIPTION OF AREA AND METHOD OF EXPERIMENT. 



The California turpentine experiments on western yellow pine 

 were conducted on the Sierra National Forest about 2 miles from 

 North Fork, Madera County. Nine hundred and sixty-eight cups 

 were hung on about 160 acres, which included several ridges extend- 

 ing from a main ridge, and ranged between 3 ; 500 and 4.500 feet in 

 elevation. No cups were hung on the few trees in the small canyons 

 between the ridges, and a few large trees with extra thick bark also 

 were left out. The stand was very open, and consisted principally 

 of mature western yellow pine with a sprinkling of young pines and 

 some scrub oak. The ground was generally free from undergrowth, 

 with the exception of occasional patches of bear clover from 6 to 18 

 inches high. Plate III shows a portion of the experimental area. 

 The number, size, and condition of the tapped trees are given in Table 

 9. Out of a total of 410 trees, 64 were fire-scarred and 47 had been 

 tapped the year before in preliminary experiments. 



TABLE 9. Number and size of tapped trees in the California experiments. 



The same procedure in hanging the cups and chipping was followed 

 as in the Arizona experiments, except that the chipping was done 

 by forest rangers and guards instead of by an experienced turpentine 

 hand. The first streak was put on July 7 and the last dipping made 

 November 1 ; during this period of approximately 16 weeks the trees 

 were chipped 16 times and dipped 8 times. 



