July 23, 1952; Pottstown, Pennsylvania.  8:40 a.m.  Witnesses:
      the two-man crews of three USAF F-94 jet interceptors. One large
       silver object, shaped like a long pear with two or three squares
       beneath it, flew at 150-180 kts.  (170-210 m.p.h.), while a
       smaller object, delta-shaped or swept back, flew around it at
       1,000-1,500 kts.  (1,150-1,700 m.p.h.).  Seen by crews for 1-4
       minutes.