 Dr. R. Cecil Gentry became the director of Stormfury in 1968 . There were no more near @-@ seedings until 1969 . In the interim , equipment was improved . What once was the primitive method of hand @-@ dumping dry ice was replaced with rocket canisters loaded with silver iodide , and then gun @-@ like devices mounted on the wings of the airplanes that fired silver iodide into the clouds . Observation equipment was improved . Additional reconnaissance data was utilized to modify the working hypothesis . The new theory took cumulus towers outside the eyewall into account . According to the revised theory , by seeding the towers , latent heat would be released . This would trigger the start of new convection , which would then cause a new eyewall . Since the new eyewall was outside the original one , the first eyewall would be choked of energy and fall apart . In addition , since the new eyewall was broader than the old one , the winds would be lower due to a less sharp pressure difference . 
