122 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1953 



destroying fungi. It is impractical to expect from such tests the degree 

 of accuracy in results that one would look for as a matter of course in 

 certain types of well conducted physical or chemical experiments. One 

 can, however, look for high reliability in the biological sense. In the half 

 science, half art of wood preservation there is as yet no generally accept- 

 able laboratory technique for measuring the preservative value of a 

 given material. Although much development work has been done, both 

 here and abroad, in an effort to promote standard laboratory procedures, 

 their proponents have had very little success in bringing into line the 

 techniques used in the various areas. The interest of the Bell System in 

 establishing a standard bioassay test will become convincingly evident 

 as this story unfolds. 



When the first American telephone lines were built there was an ade- 

 quate supply of naturally durable pole timber in northern cedar and 

 chestnut forests. The chestnut trees have been killed by a fungus disease, 

 the chestnut blight; and the chestnut supply failed completely about 

 twenty years ago. Northern cedar trees are not straight enough nor large 

 enough nor plentiful enough to meet the demands of the power and 

 communication utilities, but they are still used to some extent in the 

 Lake States area. Usually they are incised at the ground line by toothed 

 machines ; and they are then given a preservative treatment with creosote 

 or with pentachlorophenol in petroleum to prolong the life of the butt 

 and ground Une section. 



In the northern and western states the increasing demands for poles 

 35 feet and longer brought in western red cedar, a straight and nearly 

 perfectly shaped pole tree. The present Bell System use of the species is 

 relatively small, about 4 per cent of the total annual production. Butt 

 treatment of western red as well as northern cedar began in earnest 

 about thirty years ago. This procedure protects the ground section. 

 Many western cedars are now full length treated because, although the 

 species is durable, the tops and sapwood layers are subject to infection 

 and decay, sometimes after a relatively short service life. 



In the South and Southeast the great favorite is naturally the southern 

 pine pole, full length pressure-treated with creosote. Such poles made 

 their way in the Bell System as far north as Memphis and Washington 

 by the turn of the century. Their use increased rapidly after World War 

 I, and they moved into virtually all parts of the country. They now 

 make up about 73 per cent of the telephone pole plant. New treatment 

 procedures for southern pine employing pentachlorophenol in petroleum 

 applied by pressure processes are now under way at a number of plants. 



Pressure-treated Douglas fir and butt-treated western red cedar dom- 



