Each year a number of inventors are inducted into the National Inventors Hall of Fame in Akron, Ohio. This year's ceremonies, to be held May 17, will honor six living inventors and two deceased inventors. The principal invention is given with the name in the following list.

Willard H. Bennett, mass spectrometer; Gertrude B. Elion, derivatives for blocking immune response in transplants; Gordon Gould, low level laser; Leonard M. Greene, aircraft stall warning device; William Hanford Sr. and Donald Holmes, polyurethane; Elmer A. Sperry (deceased), ship gyro compass and ship gyro stabilizer; Robert R. Williams, synthesis of vitamin B1.Seven Utah inventions were awarded patents by the United States Patent Office.

A. Ray Snow, Sandy. Method and apparatus for determining whether a liquid in a reservoir is above a certain level. Assigned to Chain Tool Company Inc., North Salt Lake. Filed July 5, 1989. Patent 4,991,434.

Michael J. Pleinis, Ogden, and David M. Allen, Brigham City. Method of ultrasonically measuring thickness of zirconium liner. Assigned to Westinghouse Electric Corp., Pittsburgh, Pa. Filed Feb. 5, 1990. Patent 4,991,440.

Scott M. Packer, Provo. Diamond twist drill blank. Assigned to Smith International Inc., Houston, Texas. Filed Aug. 14, 1989. Patent 4,991,467.

Keith N. Groves, Salt Lake City. Marked baseball cover as training aid. Filed April 9, 1990. Patent 4,991,838.

William B. Leigh, Cedar City. Fluttering toy. Filed July 17, 1989. Patent 4,992,072.

Bruce H. Williams, Sandy; Glenn A. Arbanas, Salt Lake City; and Valjean P. Snyder, West Valley City. Self-clocking system. Assigned to Unisys Corporation, Blue Bell, Pa. Filed April 18, 1990. Patent 4,993,048.

Robert R. Runnells, Kaysville. X-ray tube head assembly with sterilizable handle. Assigned to MDT Corporation, Torrance, Calif. Filed Oct. 31, 1989. Patent 4,993,057.

Copies of patents are available by number for $1.50 from Box 9, Patent and Trademark Office, Washington DC 20231.