2 BULLETIN 1064, U. S. DEPARTMENT OF AGRICULTURE. 
have to-day supplanted pitch and tar, the chief products of this in- 
dusty in colonial times in the United States. 1 But the descriptive 
name, naval stores, given when these commodities were used exten- 
sively in the construction and maintenance of sailing vessels, still 
persists. That mankind has long made use of these forest products 
appears from the descriptions of the production and uses of pitch 
contained in ancient writings. 2 As long ago as the fifth century be- 
fore Christ, the pines of Macedon were a famous source of pitch. 
During the period 315 to 166 B. C, Macedon is recorded to have had 
a distinct monopoly of wood and pitch, which highly valued and im- 
portant commodities could not be exported without special permis- 
sion from the ruler. 3 Pitch was obtained by destructive distillation 
of the heartwood or of especially pitchy chips from wounded trees, 
or by driving off the water from the exuded gum. Pitch was in great 
demand for calking the seams of ships, including the war ships of 
the period, as is related in the case of the " wooden walls of Athens 
at Salamis." It was also used, for example, as a surface coating for 
altars and doors or as a sizing or lining for clay storage jars, used as 
containers for grain and other supplies. 
Until rather recently many of the methods used in the early days 
of the industry in this country were still in vogue. The cup method, 
introduced on a commercial scale about 1904, 4 has, however, of late 
largely supplanted the wasteful box system. (See PI. I, fig. 1.) 
Another much-needed improvement is seen in the tendency to reduce 
the amount of wood removed when the trees are scarified or chipped. 
The success of this practice has been demonstrated by experiments 
and the experience of progressive operators. In order to determine 
the best methods of turpentining, a comprehensive understanding of 
the tree's responses must be obtained. This involves thorough re- 
search of problems bearing on many aspects. 
PURPOSE OF THE INVESTIGATION. 
The investigation here described is concerned primarily with the 
comparison of the results of experiments with three different methods 
of chipping. It is shown that the success of a method can not be 
judged merely on the basis of the yield obtained. The maintenance 
of wood production, as indicated by growth in height and in diam- 
1 Public Record Office, London, 1610. " Instructions for suche things as are to be sente 
from Virginia." Also " Booke of the Commodities of Virginia" (cited from U. S. Dept. 
Agr. Bui. 229.) 
3 Theophrastus : "Enquiry into Plants" III, IX, 1-3 and IX, II & III. Plini : Nat- 
uralis Historia XVI. 
3 Glotz, G. : " L'Histoire de Delos d'apres les Prix d'une Denr^e." Revue des Etudes 
Grecques. Tome XXIX. Juillet-Soptembre, 1916. (Reviewed by Gerry, E. Jour. For. 19 : 
April, 1921, p. 438.) 
4 Herty, C. H. : " The Turpentine Industry of the Southern States." Jour. Franklin 
Institute. March, 1916. 
