Shortly after the experiment began to record shower data, lightning ignited the flammable liquid of one of the counters. Local firemen quickly extinguished the resulting fire before it spread to nearby trees, which were soaked with rain water. Because the trees played an essential role in suppressing atmospheric convection that would degrade telescopic observations, Harvard and MIT carried out tense negotiations, until an elaborate system of fire protection was installed, and the experiment was allowed to resume. To eliminate the threat of fire, Clark, Frank Scherb and William B. Smith created a "factory" that made nonflammable plastic scintillator disks, whose thickness was 10 centimetres (3.9 in) and whose diameter was approximately 1 metre (3 ft 3 in).