gave conclusive proof that the periodicities were actually caused by silver iodide seeding." He pointed out that these periodicities showed up when weather data from the entire country was studied, but that "the country never is uniformly affected. One state may be affected more than another."
The famed G-E Research Laboratory consultant said today that first reports of the periodic nature of the weather patterns last March and May seemed to refute earlier findings of high correlation between seeding with silver iodide crystals in New Mexico. This was because there had been no reports of periodic seeding last spring, he explained.
But a thorough study of commercial seeding operations in the West last spring proved that these seedings had been conducted periodically or at regular intervals, according to Dr. Langmuir.
He said that data supplied to the G-E weather scientists in Schenectady, N. Y., by seeding firms carrying on large scale operations in western states showed that seeding was predominant in the middle of the week during March and May, 1952.
Regular mid-week seeding took place in the Far West last March. Similar operations were carried out in March and May this year by seeders in some midwestern states.
It is possible, also, that other commercial seeders farther east took advantage of favorable clouds produced by these seedings and further intensified spaced rainfall as the weather moved east toward the Atlantic Coast, Dr. Langmuir stated.
The number of periodic seedings that took place during March and May in the West, he pointed out, "was many times more than we conducted in 1950." The periodicity of weather changes was greater during last March and May, he said, even though "the effects were not as clean-cut as they were in April, 1950." Dr. Langmuir also contrasted lais recent findings with those reported in the May issue of the "Monthly Weather Review," published by the U. S. Department of Commerce Weather Bureau. The article by F. H. Hawkins, Jr., stated that as far as could be determined, no seeding was under way last spring which could compare in periodicity with the marked spacing of rainfall at that time.
Despite this, however, Weather Bureau data gathered from the eastern states showed "a preference for precipitation to occur on Sunday with decreasing amounts on either side and no measurable precipitation on Wednesday and Thursday."
Dr. Langmuir said that extensive analysis of seeding dates supplied by seeding firms showed that artificial influencing of rainfall occurred in definite patterns throughout the West. These data disclosed that periodic seeding "was at least 20 times heavier in May, 1952, than any conducted before," Dr.