Jefferson Physical Laboratory.

The committee appointed by the Board of Overseers to visit the Jefferson Physical Laboratory on May 12 have made their annual report which has just gone to the printer.

Among the many original investigations in the Laboratory this year, the most noteworthy is the experiment made by Professor Trowbridge and his associates on the "Energy conditions necessary to produce the Rontgen Rays." For this experiment Professor Trowbridge has made a storage battery of 10,000 cells, five times as large as any similar battery heretofore used. Although this battery was made at a very moderate expense, it promises to yield results of great value in some of the most important branches of electrical sciences.

One peculiar fact was noted in connection with the steel grand stand lately erected on Holmes Field. This mass of magnetic material has caused variable disturbances in the magnetometer records of the "horizontal intensity" component of the earth's magnetism. Although this has in some ways greatly inconvenienced the original investigations which are constantly being made by the director and his staff, this difficulty will be obviated next year by the removal of the grand stands to Soldiers Field.