In an effort to determine the effect of solar disturbances upon the electrical conditions of the earth's atmosphere in relation to radio receptivity and weather changes, the Astronomical Laboratory is cooperating with the Naval Observatory, the Mount Wilson Observatory in California, and the Yerkes Observatory of the University of Chicago. The phenomena known as sun-spots, or violent gaseous convulsions on the surface of the sun, have been proved to affect radio transmission, seasonal changes, and to be a direct cause of the Aurora Borealis, or northern lights.

Daily photographs of the sun's surface are made at the Astronomical Laboratory, and forwarded to Washington with information gathered from the observations. Some of the sun-spots represent disturbed areas two or three times the diameter of the earth in extent, while the greatest one recorded at the Laboratory was about 100,000 miles long.

Assistant Professor H. T. Stetson, who has charge of the observations, states that the effect of solar eruptions, which appear as spots on a photographic negative, upon the electrical conditions of the earth's atmosphere, are known to play an important part in determining weather and seasonal changes. The Weather Bureau is making a thorough investigation of sun-spot phenomena with a view to predicting the general characteristics of whole seasons. The precipitation of rain, the recurrence of storms, and electrical disturbances in the earth's atmosphere, depend to a large degree upon the upper atmosphere, and this in turn is directly responsive to solar convulsions.

A special equipment has been installed at the Laboratory for preparing the sunspot data. After the photograph has been made the image of the sun is projected by a special optical lantern onto a white globe, so that the position of the spots on the sun's surface can be accurately determined. The number and the location of the spots, with their areas, is forwarded to Washington.