The cost of the grounding transformers and ground relays for the 6,900-volt distribution system would be about $12,000. The application to the telephone system of alternative safety measures considered would cost substantially in excess of the cost of the power system measures and does not appear justified in this case. Therefore, the cost of the telephone plant would be about the same in joint use with either power system.With the additional protective measures provided for the 6,900volt distribution system, the safety of joint use would compare favorably with that obtained under present conditions. The adoption of the higher voltage in the power system appears, therefore, to provide the best engineering solution in this case and joint use of facilities apparently may be entered into in all instances in Staten Island where the 2 services should preferably be placed on the same poles.The joint subcommittee is continuing its studies in other areas since the results of this study are not necessarily applicable where different conditions might influence the results to an important extent.The authors wish to express their appreciation to the members of their project committee and particularly to Mr. L. F. Fox and Mr. A. A. Williamson of the New York Telephone Company and Mr. J. H. Lytle of the Staten Island Edison Corporation for their assistance and cooperation in carrying out the study upon which this paper is based. Investigation of Rail ImpedancesMeasurements of impedance made on 5 sizes oi rails and on 2 types of bonds are reported in this paper; the investigation covered a range of current per rail of 20 to 900 amp, and frequencies of 15 to 60 cycles per second. Results are given in a form convenient for engineering use, and include information for applying corrections for bond impedance and for temperature.

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Results are given of observations of lightning currents, voltages, and charges in a buried cable over most of three lightning seasons. These are compared with theoretical expectations. Data regarding the incidence of lightning strokes to ground, as observed with automatic recording equipment, are also reported, together with comparisons with similar data published previously.