Great Engineers & Scientists

Frank Julian Sprague was an American inventor whose electric motors, railways and elevators revolutionized urban transportation and enabled skyscrapers to rise above cityscapes. Known as the "father of electric traction", Sprague's many accomplishments include the design of a powerful electric motor and the development of the nation's first electric railway.

Frank J. Sprague was born in 1857 in Milford, Connecticut, a small city along Long Island Sound. His family later moved to North Adams, Massachusetts, a milltown in the Berkshire Hills. A gifted student, Sprague attended Drury High School and excelled in mathematics. He then won an appointment to the U.S. Naval Academy in Annapolis, Maryland, where he enrolled in the fall of 1874. Four years later, Frank J. Sprague graduated seventh in a class of 36. As an ensign, he served aboard three different ships, where he filled a notebook with drawings of telephones, telegraphs, motors and wires; designed a DC generator called a "dynamo"; and installed the U.S. Navy's first electrical call-bell system.

Thomas Alva Edison and Frank Julian Sprague

During the 1880s, Sprague took leave from the U.S. Navy to attend the International Paris Electrical Exhibition of 1881 and London's Crystal Palace Exhibition of 1882. At the Paris show, Sprague examined inventions such as Thomas Edison's "jumbo", the engine-driven dynamo with which the Wizard of Menlo Park planned to power American cities. Frank Sprague also studied Edison's many exhibits at the Crystal Palace, serving as secretary for the jury of awards for gas engines, dynamos and lamps. In London, Sprague's ideas about motors and lamps also captured the interest of Edward H. Johnson, an Edison associate who would later serve as vice president of the Edison Electric Light Company.

In 1883, Edward H. Johnson convinced Frank J. Sprague to leave the Navy for good. As Thomas Edison's new technical assistant, Sprague joined the Edison Laboratory in Menlo Park, New Jersey, where he helped design three-wire electric lighting systems. Sprague also modified Edison's method of using mains and feeders for central-station distribution, and devised a formula for determining the ratio between wire size and current amperage. By replacing Edison's trial-and-error approach with mathematical modeling, Sprague streamlined the lab's research and development efforts. Edison was more interested in light than power, however, and Sprague left his post after only a year.

The Sprague Motor

In 1884, Frank J. Sprague started his own business, the Sprague Electric Railway & Motor Company, and rolled-out the first of several major inventions. Sprague's constant-speed, non-sparking motor with fixed brushes was the first industrial motor to maintain constant revolutions per minute (rpm) under different loads. Like Edison before him, Sprague showcased his invention, but at the Franklin Institute's Electrical Exhibition in Philadelphia. After the Edision Electric Light Company recommend "the Sprague motor . . . as the only practical and economic motor existing today", the Sprague Electric Railway & Motor company sold 250 motors in just two years.

Editor's Note: Part 2 of this biography will run next week, right here on CR4.

Resources:

http://en.wikipedia.org/wiki/Frank_J._Sprague

http://www.bera.org/articles/sprague.html

http://www.theelevatormuseum.org/e/e-1.htm

http://www.arlingtoncemetery.net/fjsprague.htm

http://americanhistory.si.edu/archives/d8069e.htm

http://files.asme.org/ASMEORG/Communities/History/Landmarks/5537.pdf

http://en.wikipedia.org/wiki/Edward_H._Johnson