Measurements of lightning, aluminum lightning-arresters, earth resistances, cement resistances, and kindred tests

During the past year investigations have been continued in the study of lightning and the operation of lightning-arresters on transmission lines. Another effort was made to supplement laboratory studies with experimental measurements on transmission lines. Two lines were chosen well up in the Rocky Mountains of Colorado as offering the greatest facilities both from the interest of the managers and the frequency and severity of lightning storms. New types of apparatus were developed for measurements and new data were collected. The object of this paper is to describe briefly the instruments and methods used in the measurement of duration, potential, current, frequency, and the theory and practise of lightning protection and earth connections with data collected during two years of study; also resistance measurements of cement under the heating effect of dynamic current, and comments on the action of lightning-arresters.