Determination of whether cosmic rays resemble electrons or photons and their origin may be settled by data collected by Albert W. Stevens, lecturer in aerophotography, and Orvil A. Anderson in their stratosphere flight Monday, according to Harlan T. Stetson, research associate in Physics, who, among others, advised Captain Stevens about his scientific instruments when he was at Harvard last spring.
Dr. Stetson explained that there are two conflicting theories, Arthur Compton, of the University of Chicago, believing that cosmic rays are chiefly made up of electrons, and Millikan believing that they are chiefly made up of photons, bundles of light energy.
New films made on the expedition should help to settle the controversy. Possibly there may be some of both.
Captain Stevens carried on the ascent a specially constructed spectroscope, the details and mounting of which were planned in connection with Dr. Stetson among others.
The gendels of the balloon in this flight was above ninety-seven per cent of the earth atmosphere, and thus a spectrum of the sun could be obtained which would be free from practically all interference. It is hoped that the ultra-violet ray end of the spectrum may have been observed with greater accuracy.
Only about two per cent of the earth's atmosphere was above the explorers and absorption due to ozones is believed to be less at such a high altitude, and as the air particles would be very thin, there would be no interference with the rays of the sun.
On many occasions before this Captain Stevens has taken pictures of the curvature of the earth with the aid of infra red rays. In the hall of the Geographical Institute among a collection of his aerial pictures there is one example of the curvature. Pictures taken on this flight from such a great height should produce much better studies of this phenomenon.
Dr. Stetson explained that the reason all the sky was dark at such a height above the ground was that there were no air molecules or dust particles in the air to diffuse the sun's rays. Thus the only place the explorers could see light in the sky was by looking directly into the sun, which had the appearance of a searchlight. They were on the upper side of what we or dinarily call the blue sky, in the words of Dr. Stetson.
Captain Stevensswill return to Harvard this spring to deliver his regular lecture in aerophotography and will have his headquarters in the lustitute of Geographical Exploration.