Fog is one of the great enemies of transportation, be it of aeroplanes or cars on a motorway. Much effort, therefore, has been expended over the years in trying to find ways of getting rid of it - but with only very limited success. Fog will disperse, for example, if the air in the vicinity is heated sufficiently to allow the tiny water droplets to evaporate. One technique used at airports involved using petrol burners placed at regular intervals along a runway to increase the temperature and "burn away" the fog.
To some extent it worked, but because of the great amounts of heat required to produce the desired effect, vast quantities of fuel were used, and for most purposes it was prohibitively expensive. A more adventurous technique was devised some years ago by one William Bellis of New Jersey. He became aware of the experiments with "fogdrip" described, you may remember, in this column a day or two ago. These consisted of extracting water from the camanchaca - a veil of cloud or fog that shrouds the hills along the coast of Chile. The fog droplets are caught by a nylon mesh stretched upon a wooden frame; in due course millions of the tiny droplets coalesce to larger drops which run down the mesh to troughs, from which the precious water is drawn to supply the nearby villages. One foggy day, Bellis realised that if one of these nylon frames could collect water at a rate of several gallons per square yard per hour, then, when this water was removed, it followed that the fog must be less dense - at least in the area where the frames were sited. Why not use the concept as a way of improving visibility on motorways or airport runways? When put into practice, the methodology involved "fog-brooms", as the rotating nylon-covered frames were called; as these "brooms" were made to spin around, the theory was that they would extract the excess moisture from the air. The authorities were sufficiently impressed with Bellis's ideas that in the autumn of 1965 20 rotating fog-brooms were installed along the length of Parkway Avenue, Trenton, in New Jersey.
The "broom-farm", if one might call it that, was automatically controlled by photoelectric switch, so that the fog-brooms began to whirl whenever visibility decreased below a certain level, and were turned off again whenever the fog began to disappear.
Unfortunately, although the idea was clever, this bizarre attempt to control the elements never worked effectively. Today not a single one of Bellis's brooms can be seen to grace the kerbside of Parkway Avenue, Trenton, USA.