Early History -4- 



heated oleic acid and similar substances up to about 200°C and passed a 

 stream of air over them to get the vapor mixed with air. Then they quenched 

 the mixture suddenly by blowing in a large amount of cold' air. The parti-5 

 cles grew in size and by sudden quenching they found they could stop the 

 growth at any desired point and also make particles of very small size. 

 They were surprised to find that, under certain conditions, they could get 

 particles of extraordinarily uniform size. 



Further work and experimentation showed that they could do the same 

 thing on a large scale. Larger generators were built, tests were made, and 

 the design was adopted by the Army and used successfully and on a large 

 scale during the war/ 12 ' 



PRECIPITATION STATIC 



■Quite independently of this work the Secretary of War asked in 1943 

 for research into the problems of precipitation static. ^2) it W as believed 

 that the invasion by Japan would have to come very largely from air attacks 

 through the Aleutian Islands, across Alaska, and from the North. That led to 

 a tremendous development of air transport and airplanes through the Aleutians. 



The difficulty in flying aircraft in the Aleutians was very serious. One 

 of the big problems was icing of the aircraft, but even more baffling was the 

 complete loss of radio contact when the planes flew through snowstorms. The 

 planes might become charged, sometimes, to a potential of 250,000 volts or 

 more, producing corona discharges from all parts of the plane and causing such 

 electrical disturbances that radio sets could not receive messages. Pilots had 

 particular difficulty in finding their bases and getting down through this foggy 

 bad weather. What could be done about it? 



Langmuir and Schaefer were interested. They had no particular ideas 

 on the subject, except that it had to do with weather. In their opinion, the best 

 place to investigate something like that was the well-equipped laboratory of the 

 Mt. Washington Observatory on top of Mount Washington in New Hampshire. 



Mount Washington in winter has an average temperature of minus four 

 or five degrees F, the wind averages about 60 miles per hour, and most of the 

 time clouds sweep over the summit. It seemed to offer the proper conditions 

 for a research of this kind. 



So equipment was installed at the summit, and Schaefer went there sev- 

 eral times during the winter of 1943 to conduct experiments. But he discov- 

 ered that anything exposed there during the winter immediately became cov- 

 ered with ice, because the air was full of supercooled water droplets. He and 

 Langmuir became so much interested in this that they hoped they would not 

 have to continue a long study of precipitation static. 



