PENETRATION AND DECAY 375 



Table I is a summary of the data on locality, age, creosote penetra- 

 tion, and incidence of decay for 3102 telephone poles in line in the 

 eastern part of the United States. The pole groups are based on 

 years in service and geographic settings. 



Figures 3 to 7 are records of the penetration and the condition of 

 each of the 3102 poles at the time they were inspected. Five age 

 groups are represented, from 7.7 years to 26 years, respectively. 

 These records are graphic illustrations of the fact that the failed poles 

 and the decaying poles had poor penetration. Each solid dot repre- 

 sents a single pole failure, and each hollow dot represents a single 

 infected pole. For example, in Fig. 3 for poles in line ten years or less, 

 the figures and symbols in the 0.8 inch and 25 per cent block mean 

 that there were five poles having penetration 0.8 inch and 25 per cent 

 of the sapwood thickness ; and of these five poles two were sound and 

 three were so badly deteriorated that they had to be removed. 

 Similarly in the 0.7 inch and 25 percent block, two of the three poles 

 were failures and one was infected. 



The crosses in the 100 per cent line indicate poles with a little heart- 

 wood decay or with slight external decay at the ground line. 



The broken lines in Figs. 3 to 7 delimit the individual data for poles 

 having penetration less than 1.8 inches and 60 per cent of the sapwood 

 thickness, and less than 2.5 inches and 85 per cent of the sapwood 

 thickness, respectively. The latter is the minimum penetration 

 called for in current American Telephone and Telegraph Company's 

 specifications for creosoted southern pine poles. 



The abscissa in each of the five figures has been warped beyond 2.4 

 inches in order to condense the charts to reasonable proportions for 

 reproduction. Complete data on the range in penetration for the five 

 age groups are shown in the form of frequency cur\'es in Fig. 8. The 

 15-year sample from the Petersburg, Virginia-Denmark, South Caro- 

 lina, line obviously has the poorest penetration of the five groups. It 

 also had the highest per cent of pole failures, as shown by Table II. 



Table II is a summary of the number and per cent of the 3102 poles 

 in which the sapwood had been penetrated less than (o) 1.8 inches and 

 60 per cent, (b) 2.5 inches and 85 per cent, (c) 3 inches and 90 per cent, 

 and {d) 3.5 inches and 90 per cent; and it also shows the per cent 

 of poles with 100 per cent sapwood penetration, as well as the pene- 

 tration in the poles that failed. 



Table III contains typical analyses of creosote used in treating the 

 poles. 



