The Birmingham age-herald., 1923-03-19
CONTROL IF RAIN MAY RESULT FROM
 NE ENTERTAINMENTS
Clouds Are Made to Disappear and Moisture Descend by Electric Process Used by
 the Scientists

DAY TON, O., March 1S.-(By As sociated Press.)-Precipitat has been caused and clouds have been made to disappear in a series of ex- periments which are being conducted here at McCook Field, according to announcement made by the experi- mentors, Prof. Wilder D. Bancroft. of Cornell University, and l.. Francis Warren. The successful experiments were made with the cooperation ot the army air service.
 Results of the experiments were described as Absolutely uncanny" by observers at the army air field In brief, the clouds were made to dis appear and precipitate their moisture by the dropping of electrically charged grains of sand upon them from airplanes.
 Professor Bancroft and Mir. War ren claim that the process will be of great value in the commercial world. as fogs over cities, harbors and flying fields can be made to dis appear, thereby insuring safety to travel and transportation. They do not claim that in every instance rain CT precipitation can be produced, as they say all clouds do not contain sufficient moisture. Some of the ex- periments demonstrated that while slight precipitation was caused, this precipitation was evaporated before 1t reached the earth.
 Patents Pending.
 In payment of it's cooperation dur ing the tests. the army air service has been given the free use of the process, for which patents are pend ing, for the removal of mists and fogs over it's flying fields
 The experiments have been in prog ress at McCook Field here for the last year and half, and will be con- tlnued at Moundsville, W. Va, on the Washington-Dayto air route. and possibly at Washington, where fog conditions arc more frequent and better than at Dayton
 In making the announcement of his successful experiments. Mir War ren said that elaborate scientific re- searches have shown that particle of atmospheric moisture carrying an electric charge has tendency to grow in size. even under conditions adverse to enlargement as to cause unchanged drops to evaporate. the theory being that the electric charge diminishes the surface tension of the drops and thus facilitates further condensation and coalescence.
 Sand is Used.
 In the experiments, La Pere plane carrying about 80 pounds of sand, of about 150 mesh, with wind driven generator operating an electric equipment capable of charging the sand with high voltage, either posi- lively or negatively. at the will of the operator, was employed. The sand was charged to approximately ot, n Or0er of .0006 electric static units per grain, and was scattered through the action of the plane propeller at height Of about 500 feet above the tops of the clouds, the plane travelling at rate of about 100 miles per hour.
 The time taken to precipitate ana destroy the clouds, from the period of the first direct attack to the period of final disappearance, in each case rarely exceeded ten minutes and in several cases was less than five nm utes, MT. Warren said. He pointed out that the temperature and gen eral climatic conditions were vari- able, as Shown by the months of the recorded experiments: April 15. June 2s, July 1S, August 1, August 5, No- vember 14, and other times, as shown by affidavits of air service officers and others.
 The clouds dealt with, MT. War ren said, varied from several thousand feet in length and breadth. to several miles; the thickness from 500 feet to 1.50o feet;, tho altitude from 2soo to 10000 feet, and par took for the most part of the nature oA Cumulus and Stratus. or haze like clouds, which consist of fog in horizontal stratum, all contain ing slight moisture which was quick ly evaporated in the dry air above the clouds. Some of the experiments. MT. Warren said. were followed by snow flurries over the flying field, and light rainfall over the adjacent regions. Coarse sand that will fall rapidly over definite locality, there- by producinE quick results. will be employed for foEs and mists. MT. Warren announced. Sand powdered to sizes that win fall by gravity slowly through the varying winds and be widely dispersed, will be employed for artificial rain making. One or more tons of minute dust particles as fine or finer than tal- cum powder and having trillions of particles per cubic centimeter that, whom scattered. will cover enormous