Corrosion of cable sheath in creosoted wood conduit

Following the successful use of conduit of creosoted yellow pine in the eastern and southern part of this country, similar duct made of Douglas fir was introduced on the Pacific Coast in 1911. Manufacture was undertaken in the Puget Sound territory; and extensive use of the duct has since been made for both main and subsidiary communication subways in all parts of Washington, Oregon and California, excepting Southern California where its field has been limited by economical considerations to lateral or subsidiary construction. This conduit was also considered satisfactory, until the latter part of 1923, when corrosion developed on some newly placed telephone cables, and the attending circumstances were such as to indicate that the duct itself might be responsible. It is with the identification of this corrosion and the determination and application of methods of allaying it that this paper is concerned.