Two inventions without which mass transportation could quickly become mass disaster -- the traffic light and the subway train's third rail -- were both conceived by black inventors, whose contributions to U.S. patents have been significant

The third rail, so important to the development of electric railways and the subway, was patented in 1901 by Granville T. Woods (1856-1910) of Columbus, Ohio.

Woods ultimately patented more than 50 inventions, most of which were electrical devices intended for use by the railroad industry.

Although Woods never completed his elementary school education, he became a machinist and blacksmith by trade. He later studied mechanical and electrical engineering for two years in college, and sold one of his inventions to the telephone company. Woods used the profits from that transaction to start the Woods Electric Co., which manufactured and sold telephone and other electrical equipment in the late 1800s.

The patent for the basic traffic signal was granted on Nov. 20, 1923, to Garrett A. Morgan (1875-1963) of Paris, Tenn., and Cleveland.

Mrs. Patricia Ives, a patent examiner in the U.S. Patent Office and an authority on black inventors, recently provided a report which shows 847 patents were awarded to 329 black inventors in the United States between 1821 and 1976.

The first patent obtained by a black inventor was granted in 1821 to Thomas L. Jennings, a New York tailor, for a cloth for dry scouring of clothes.

In 1834, Henry Blair of Glenross, Md., received a patent for a "seed planter." Two years later, Blair received another patent for a "cotton planter."

George Washington Carver, who is well known for his achievements in agricultural science, received three patents in the 1920s relating to paint stain removal.

Another patent granted to a black inventor in the transportation area went in 1949 to Frederick McKinley Jones of Cincinnati for a truck air conditioner.

Since 1976 at least another 100 black inventors have received a total of nearly 100 patents. Among the most recent were John A. Jefferson of the District of Columbia, who received a patent for a "motorcycle ice chest;" Eugene Williams Sr., of Columbia, Md., who invented an "audiovisual interview portfolio," and Emanuel L. Logan of Alexandria, who has received numerous patents, five of them relating to door locks.

Recent patents awarded to inventors in Maryland and Virginia: Maryland Inventors

Norwood R. Warehimes of Baltimore. Turnstile Coal and Games Usage. Patent No. 4,344,628. 5 Claims.

Albert R. Parks of Glen Burnie. Organotin Antirouling Coating with Epoxy and Polyacrylate Compositions. Patent No. 4,344,875. 5 Claims.

Lo I. Yin of Silver Spring. Low-Intensity X-Ray and Gamma-Ray Spectrometer. Patent No. 4,345,153. 33 Claims.

Augustus S. Bainbridge of Baltimore. Bias-Compensated, Ionization Sensor for Gaseous Media and Method for Attaining Proper Bias for Same. Patent No. 4,345,154. 19 Claims. Virginia Inventors

Robert A. Chronowski of Great Falls. Fluidized Bed Combustion Device. Patent No. 4,344,372. 3 Claims.

James Perrin of Fairfax. Log Supporting Rack for Use in a Fireplace. Patent No. 4,344,412. 6 Claims.

Leo M. Moore of Ashland. Integral Heater Follower Plate. Patent No. 4,344,547. 6 Claims.

Liam R. Jackson of Newport News. Multiwall Thermal Protection System. Patent No. 4,344,591. 15 Claims.