190 Alaskan Science Conference 



In 1948 the seismographs were moved to the new magnetic 

 observatory of the Coast and Geodetic Survey. Records are still 

 being made of all tremors and are reported to Washington. In 

 the near future the Geophysical Institute will collaborate with 

 this observatory and study the data. 



State of the Atmosphere in the Arctic 



Work on the state of the atmosphere in the Arctic was pro- 

 posed in 1948-49. The problem has been attacked along several 

 lines: 



(1) The Exploration of the atmosphere into the mesosphere by 

 probing with a searchlight 



Experiments to determine the atmospheric density, composi- 

 tion, temperature, and polarization, in the height range between 

 30 and 100 kilometers are underway. Two 60 inch General 

 Electric Company searchlights were made available through 

 the Airforce Cambridge Research Laboratories. One serves as 

 a transmitter, but the original carbon arc has been replaced by 

 three high pressure quartz mercury arcs. The other has been 

 modified so serve as a receiver; an elliptical mirror has been 

 mounted so as to collect the light from the large mirror and 

 focus it upon an electron multiplier type phototube. This 

 equipment, with attached electronic components, is designed 

 to enable explorations up to approximately 100 kilometers. Pre- 

 liminary work at lower altitudes has given satisfactory results. 

 In connection with this project, the theory of the scattering of 

 light by atmospheric gases has been re-examined. It may be of 

 interest to remark that the best results have been obtained at 

 the isolated stations when the atmosphere is clear, still and at 

 a temperature of about 40 ° below zero Fahrenheit. The results 

 have been given in detail in the progress reports on the State 

 of the Earth's Atmosphere in the Arctic. In general the results 

 verify those of the NACA. 



