. Bell telephone magazine . tion of circuit including transmission equivalents, width offrequency band transmitted, and limits of echoes, phase distor-tion, crosstalk, noise and of range of transmission level. Thisseems to be an advantageous method of approach, particularlyin view of existing differences in practice in different countriesin such things as the design of cables and of loading systems,and the rivalry between different manufacturing organizationsin Europe in the development of improved systems. Accom-panying the recommendations just outlined are fundamentaldefinitions of the units
. Bell telephone magazine . tion of circuit including transmission equivalents, width offrequency band transmitted, and limits of echoes, phase distor-tion, crosstalk, noise and of range of transmission level. Thisseems to be an advantageous method of approach, particularlyin view of existing differences in practice in different countriesin such things as the design of cables and of loading systems,and the rivalry between different manufacturing organizationsin Europe in the development of improved systems. Accom-panying the recommendations just outlined are fundamentaldefinitions of the units, terms and methods of measurementnecessary for defining the electrical characteristics of the cir-cuits. An important part of the C. C. plant recommendationsrelates to the maintenance of the circuits, giving maintenanceroutines, methods of test and specifying even the tests on local 247 BELL TELEPHONE QUARTERLY EUROPEAN INTERNATIONAL TELEPHONE CABLES. 1929 FROM MAP PREPARED BY BUREAU OF THEINTERNATIONAL TELEGRAPH UNION. circuits and subscribers stations. The information for themaintenance of long international circuits is now being activelyexpanded. Other recommendations relate to the linking of radio and 248 INTERNATIONAL CO-OPERATION IN TELEPHONY wire circuits, to the use of telephone and telegraph in the samecables, and to the requirements for special services includingprogram circuits and picture transmission circuits. One volume of C. C. I. recommendations contains provisionsfor co-ordinating international telephone circuits with powerand electrified railroad circuits so as to avoid provisions have resulted from the co-operative work ofthe telephone representatives with representatives of inter-national organizations of power companies and railroads. An-other volume contains proposals regarding means to avoidelectrolytic and chemical corrosion of cable sheaths. Conclusion Although the life of the International Advisory Committeehas not been long, it
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