352 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1961 



It was concluded that though there was some difference in penetra- 

 tion due to wavelength, there was little likelihood of finding any visual 

 light that would penetrate thick, dense fog. Dr. Stratton's further 

 investigations gave some promise that at very short wavelengths — 

 below 1 centimeter — there was a possibility that fog might be pene- 

 trated by dispersal. In addition to the scientific studies carried out, 

 various inventors presented ideas for fog penetration, all of which 

 received careful consideration. 



Four basic methods of fog dispersal were originally considered : 



1. Dispersal by mechanical means. — Here the concept was to have a 

 large propeller or series of propellers "churn up" the fog. 



2. Dispersal hy chemical means. — Experiments carried out by 

 Henry G. Houghton, Jr., of MIT, using hygroscopic materials, showed 

 some promise both in the laboratory and in full-scale tests that were 

 conducted on the estate of Colonel Green in South Dartmouth, Mass. 



3. Dispersal hy electrical means. — From the early 1920's Dr. War- 

 ren of Hartford, in collaboration with the Army Air Service, had 

 been experimenting with cloud and fog dispersal by means of electri- 

 fied sand particles dropped from an aircraft. He was occasionally 

 successful in dispersing small clouds. Mr. Flowers experimented 

 with fog dispersal through the use of electrified water particles and 

 achieved some interesting results. 



4. Dispersal hy heat. — Experimentation on, and the actual accom- 

 plishment of, fog dispersal by heat has been carried on until fairly 

 recent times. 



FIDO (Fog, Intense Dispersal Of) was effectively used in World 

 War II on 3 of the long emergency fields and 10 main landing fields 

 in England. It consisted of powerful heat sources at intervals along 

 the runways which heated the air to a temperature above the dew- 

 point, thereby dispersing the nearby fog. Approximately 2,500 

 bombers and fighters — mostly RAF but including some USAF — re- 

 turning from missions and finding their home base (and much of 

 England) covered in pea-soup fog were directed to the cleared "tun- 

 nels in the fog" over these FIDO fields and landed safely. 



Perhaps I should mention here that the Eighth Air Force Bomber 

 units in England were being trained and equipped to operate "blind" — 

 without FIDO — and at the end of the war two groups could take off 

 and land regardless of fog. Shortly the entire force would have been 

 so trained. 



In the late 1940's successful FIDO experiments were carried out 

 at the Naval Air Base at Areata on the coast of northern California. 

 Areata was chosen because it was in one of the foggiest areas on the 

 entire Pacific coast. Southwest Airways successfully used the Navy 

 fog-dispersal system from November 1947 until November 1949. 



