10 



WESTERN PINES AS A SOURCE OF NAVAL STORES. 



The average yield of dip from the four crops of 8,000 cups each 

 was 65,267 pounds, or 0.263 pound per cup per week. This makes 

 the yield from western yellow pine 82.5 per cent of that obtained 

 from southern yellow pine. In making this comparison the same 

 unit of time is used in both cases, that is, the flow per cup per week. 

 In order that the yield per crop from Arizona and Florida may be on 

 a comparable basis the Arizona yield of 7,817.5 pounds from 1,500 

 cups may be expressed as the equivalent of a crop of 8,000 cups or 

 41,700 pounds. This is 64 per cent of the average yield secured in 

 the Florida experiments during the season of 1905. In the Arizona 

 experiments the first chipping was done May 8 and the last dipping 

 made October 31. Had the cups arrived earlier they could have 

 been hung in April and the season lengthened to 26 weeks instead 

 of 24. 



COMPARISON OP YIELDS OF SCRAPE IN ARIZONA AND FLORIDA. 



Table 5 shows the amount of scrape collected from the experimental 

 areas and the percentage of faces bearing scrape in sufficient quantity 

 to collect. 



TABLE 5. Scrape obtained from western yeiiow pine in Arizona. 



Of the 1,500 faces on the three experimental areas 990 had sufficient 

 scrape on them to warrant removing it. The total yield of 1,126.75 

 pounds of scrape from 1,500 faces chipped 24 times is equivalent to 

 an average yield of 0.031 pounds per face per week. Reduced to a 

 common basis the Florida experiments (see Table 4) show a yield of 

 0.034 pound of scrape per face per week. Hence the average produc- 

 tion of scrape per face in the Arizona experiments was 91 per cent of 

 that in the Florida experiments, if the yields are compared for equal 

 periods of time. 



The total yield of 1,126.75 pounds of scrape from 1,500 faces is 

 equivalent to a yield of 6,014 pounds of scrape from a crop of 8,000 

 faces. Table 4 shows that the weight of scrape obtained in the 

 Florida experiments averages 8,338 pounds per crop of 8,000 faces. 

 The yield from western yellow pine is therefore 72 per cent of that 

 obtained from southern yellow pine when the comparison is made 

 on the basis of the whole season. 



