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CARNEGIE INSTITUTION OP WASHINGTON. 



of matter from both the physical and the astrophysical points of view. 

 Throughout the winter there were constructed in the laboratory in Pasadena 

 special self-registering instruments for obtaining records of the penetrating 

 radiation, the temperatures, and the pressures at all heights up to 20 kilo- 

 meters. These instruments with their driving and recording mechanism 

 weighed but 190 grams each, the success attained in reducing weight 

 being due in no small degree to the skill of Dr. Millikan's assistant, Mr. 

 Ira S. Bowen, and of the head mechanician, Mr. Julius Pearson. In flights 

 made at Kelly Field with these instruments, during the first two weeks in 

 April, Mr. Bowen and Dr. Millikan,who conducted them, attained altitudes of 

 about 17 kilometers, approximately twice as great as those attained by any 

 previous observers. These results show that the amount of this penetrating 

 radiation existing at these high altitudes is much less than had been supposed. 

 Parallel with these observations Mr. Russell M. Otis has, under the direction 

 of Dr. Millikan, made similar observations in airplanes, in manned balloons, 

 and on mountain tops, with results which are, as far as they go, in agreement 

 with the results obtained by the altitude flights made by Mr. Bowen and 

 Dr. Millikan. It is proposed to push these interesting studies on penetrating 

 radiations during the coming autumn and winter. They have already yielded 

 results which seem to be of much interest and importance. 



In order to carry out the large amount of work, both of construction and of 

 observation, involved in the researches described above and in those planned 

 for this fall, a considerable portion of the time of two mechanicians (who have 

 been added to the shop for the purpose) and a group of young observers have 

 been employed. The chief of these last is Mr. Bowen, the major portion of 

 whose time has been devoted to these researches. Mr. Otis has been employed 

 on them for part time, and this autumn it has been arranged to take on four or 

 five others, on part time, in the same way. It is proposed to carry out as 

 rapidly as possible the general program submitted last year. 



Nichols, E. L., Cornell University, Ithaca, New York. Report on studies in 

 luminescence. (For previous reports, see Year Books Nos. 4-20.) 

 The Luminescence of Incandescent Bodies. 



Throughout the year covered by this report the phenomena connected with 

 luminescence at high temperatures have been under further investigation. 



It has been found that when certain refractory oxides and other compounds 

 are heated in the oxy-hydrogen flame to temperatures above those at which 

 the blue glow 1 occurs, there are further noteworthy departures from the 

 relations which pertain to ordinary temperature radiation. 



This is true of the oxides of the following elements, which are members of 

 groups II, III, and IV of the periodic table: 



'See Year Book 20, p. 462; also Nichols and Howes, Journal of the Optical Society of America, 

 vol. vi, p. 42 (1922). 



