24 BULLETIN 1061, U. S. DEPARTMENT OE AGRICULTURE. 
Table 11 assumes that well-stocked stands are heavily cupped 
with one cup to every tree measuring 7. 8. or 9 inches in diameter, 
one cup on about one-half of the 10-inch trees and two on the re- 
mainder, and two cups on all trees 11 inches and over. The figures 
are for the first year's working. At 30 years, for example, the aver- 
age yield per crop (10.000 cups) is shown to be 53.000 pounds of gum. 
which makes in turn about 26.5 barrels of spirits of turpentine 4 and 
88 barrels of rosin. This is obtained from 210 cups per acre, each 
yielding 5.3 pounds of gum during the season. This number of 
cups was hung on 210 trees out of a total stand of 355 trees per acre. 
At 40 years, a yield of 34 barrels of turpentine may be expected. 
The yield per acre at 30 years was 1.122 pounds of gum. producing 
about 28 gallons of turpentine and 1.9 barrels of rosin. These yields 
The production of turpentine and rosin has shown 
a marked downward trend for some 15 years. This 
is due chiefly to the exhaustion of virgin timber. 
The very wasteful and destructive methods generally 
employed w T ith both old timber and second growth 
have ahvays meant a total production much below 
what w T ould be possible under a more conservative 
system. If the rate of decrease continues, within the 
next decade or so the United States will lose its com- 
manding position in the w T orld's market and may in 
time be unable to supply its domestic requirements. 
seem to be very fair in comparison with the average of about 40 
barrels of spirits per crop yielded by the better class of mature 
stands under good working in the Gulf region, and an average for 
all timber of about 20 barrels per crop. The inclusion of small 
sizes of trees and very close cupping should not be taken as any 
recommendation for operating such 'young stands as a general prac- 
tice. The figures are given as an indication of what might be ex- 
pected in working thick stands of young timber before thinning or 
clearing up the land. 
On the Florida Xational Forest the longleaf pine of all ages and 
sizes, 10 inches and over in diameter, in a certain contract yielded 
a virgin working of 96.000 pounds of gum per crop, which gave 48 
barrels of spirits and 134 barrels of rosin. This was an average yield 
4 By a coincidence this is the same yield as shown by the 1910 United Slates census 
for the average crop in Georgia, where much of the production is from second-growth 
timber. 
