. The Bell System technical journal . Iin. Dirtirt lUituchrtim npn ■lurtion ,,i a staiiuil spcciinoii ofSiiiiihcm Yellow Pine showing sap-stain Inngus niycclinni. Magnification 100 X. This particular fungus is harmful to the extent that it causes a discolorationof the sapwood, which assumes a blue color in place of the usual straw-yellow.\\cK)d-destroying fungi differ somewhat in their appearance from the S^^^ Fig. M. Direct pliotuniicr^Kfaphy Ij ihc autochromc process of aradial sectif>n of mahogany wood. Magnification 50 X. Mahogany is one ofthe best of ca
. The Bell System technical journal . Iin. Dirtirt lUituchrtim npn ■lurtion ,,i a staiiuil spcciinoii ofSiiiiihcm Yellow Pine showing sap-stain Inngus niycclinni. Magnification 100 X. This particular fungus is harmful to the extent that it causes a discolorationof the sapwood, which assumes a blue color in place of the usual straw-yellow.\\cK)d-destroying fungi differ somewhat in their appearance from the S^^^ Fig. M. Direct pliotuniicr^Kfaphy Ij ihc autochromc process of aradial sectif>n of mahogany wood. Magnification 50 X. Mahogany is one ofthe best of cabinet woods and finds wide application in the telephone plant. A Clock-Controlled Tuning Fork as a Sourceof Constant Frequency By J. G. FERGUSON Notk: The art of electrical conimunication employs such a wide varietyof methods for the transmission of intelligence that it utilizes alternatin);currents whose fre<iuencies cover the entire range l)ctwecn a few cycles persecond and several million. With the increasing use of these methods, itiKcomes more and more imperative that determinations of the frequencyof any alternating current may Ik made with extreme accuracy. In piir-ticular, recent developments in carrier current telephony and telegraphyover wires have placed exceedingly rigorous limits on the frequency adjust-ment of certain typxrs of apparatus. It is many times necessary to holdsuch c<)uipment as oscillators
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
