Important discoveries have recently been made in the Engineering School laboratories relative to high voltage underground cables, which are the subject of a special study in cooperation with the National Electric Light Association, the American Institute of Electrical Engineers, and the Association of Illuminating Companies.

The Engineering School is one of three technical Institutions chosen in 1923 to carry on the cable experiments, and a committee representing practically the entire electrical industry keeps in constant touch with the progress of the work.

The problem of supplying modern cities with electrical current has become increasingly complicated, according to Assistant Professor C. L. Dawes, who has charge of the experiments. Electrical currents of as high as 220,000 volts are now carried a considerable distance on overhead wires, and currents of 500,000 volts will probably be handled in the near future.

While these high voltage wires can be employed in the outskirts of a city, they are too dangerous and impractical for use in the city streets. The result has been an increasing employment of underground cables, but these are at present imperfectly developed, and involve difficulties when used for extremely high voltages.

The most serious problem connected with the underground transmission of a high voltage electric current is the deterioration of the insulating material, and this is the special study being made at the Engineering School

H. H. Reichard, a graduate of Pennsylvania State College, is at present conducting the experiments, for which a variety of special apparatus has been developed. Recent important discoveries have been made in the effect of the current upon the paper insulation, and a previous belief that lead cable covering increased the efficiency of the cable has been disproved.

Professor Dawes states that the development of a cable covering which will not be deteriorated by the current, and not waste electric energy, is the purpose of the experiments.