Frank J. Sprague

"Frank Sprague" redirects here. For the guitarist, see Frank Lee Sprague.
Frank Julian Sprague

Frank Julian Sprague (1857–1934) American inventor, Father of Electric Traction
Born (1857-07-25)July 25, 1857
Milford, Connecticut
Died October 25, 1934(1934-10-25) (aged 77)
Residence United States
Nationality American
Fields Electrical engineering
Alma mater United States Naval Academy[1]
Known for Electric motor
Notable awards Elliott Cresson Medal (1903)
IEEE Edison Medal (1910)
Franklin Medal (1921)
John Fritz Medal (Posthumous, 1935)

Frank Julian Sprague (July 25, 1857 in Milford, Connecticut – October 25, 1934)[2] was an American naval officer and inventor who contributed to the development of the electric motor, electric railways, and electric elevators. His contributions were especially important in promoting urban development by increasing the size cities could reasonably attain (through better transportation) and by allowing greater concentration of business in commercial sections (through use of electric elevators in skyscrapers).[2] He became known as the "Father of Electric Traction".

Early life and education

Sprague was born in Milford, Connecticut in 1857 to David Cummings Sprague and Frances Julia King Sprague. He attended Drury High School in North Adams, Massachusetts and excelled in mathematics. In 1874, he won an appointment to the United States Naval Academy in Annapolis, Maryland. There, he graduated seventh (out of thirty-six) in the Class of 1878.[3]

United States Navy, inventor

Frank J. Sprague, notes on seamanship, with drawings of sail boat parts, and electrical equipment, 1878-1880
Notes on seamanship, with drawings of sail boat parts, and electrical equipment, by Frank J. Sprague, 1878-1880

He was commissioned as an ensign in the United States Navy. During his ensuing naval service, he first served on the USS Richmond, then the USS Minnesota. While his ship was in Newport, Rhode Island, in 1881, Sprague invented the inverted type of dynamo. After he was transferred to the USS Lancaster, flagship of the European Squadron, he installed the first electric call-bell system on a United States Navy ship. Sprague took leave to attend the International Exposition of Electricity of 1881 in Paris and the Crystal Palace Exhibition in Sydenham, England in 1882, where he was on the jury of awards for gas engines, dynamos and lamps.

Electrical pioneer

In 1883, Edward H. Johnson, a business associate of Thomas Edison, persuaded Sprague to resign his naval commission to work for Edison. One of Sprague's significant contributions to the Edison Laboratory at Menlo Park, New Jersey, was the introduction of mathematical methods. Prior to his arrival, Edison conducted many costly trial-and-error experiments. Sprague's approach was to calculate using mathematics the optimum parameters and thus save much needless tinkering. He did important work for Edison, including correcting Edison's system of mains and feeders for central station distribution. In 1884, he decided his interests in the exploitation of electricity lay elsewhere, and he left Edison to found the Sprague Electric Railway & Motor Company.

By 1886, Sprague's company had introduced two important inventions: a constant-speed, non-sparking motor with fixed brushes, and regenerative braking, a method of braking that uses the drive motor to return power to the main supply system. His motor was the first to maintain constant speed under varying load. It was immediately popular, and was endorsed by Edison as the only practical electric motor available. His regenerative braking system was important in the development of the electric train and the electric elevator.

Electric streetcars

Postcard of electric trolley-powered streetcars of the Richmond Union Passenger Railway in Richmond, Virginia, in 1923, two generations after Frank J. Sprague successfully demonstrated his new system on the hills in 1888. The intersection shown is at 8th & Broad Streets.

Sprague's inventions included several improvements to designs for systems of electric streetcars collecting electricity from overhead lines.[4] He improved designs for a spring-loaded trolley pole that had been developed in 1885 by Charles Van Depoele, devised a greatly improved mounting for streetcar motors and better gear designs,[4] and proved that regenerative braking was practical. After testing his trolley system in late 1887 and early 1888, Sprague installed the first successful large electric street railway system – the Richmond Union Passenger Railway in Richmond, Virginia, which began passenger operation on February 2, 1888.[1] Long a transportation obstacle, the hills of Richmond included grades.of over 10%, and were an excellent proving ground for acceptance of his new technology in other cities, in contrast to the cable cars which climbed the steepest grades of Nob Hill in San Francisco at the time.

By the summer of 1888, Henry H. Whitney of the West End Street Railway in Boston had witnessed the simultaneous startup of multiple streetcars on a single power source, and had signed up for conversion.[5]:10 By January 1889, Boston had its first electric streetcars, which were so popular and noteworthy that poet Oliver Wendell Holmes composed a verse about the new trolley pole technology, and the sparking contact shoe at its apex:[5]:10

Since then on many a car you'll see
A broomstick as plain as plain can be;
On every stick there's a witch astride—
The string you see to her leg is tied.

Within a year, electric power had started to replace more costly horsecars in many cities. By 1889 110 electric railways incorporating Sprague's equipment had been begun or planned on several continents. In 1890, Edison, who manufactured most of Sprague's equipment, bought him out, and Sprague turned his attention to electric elevators. However, he continued to be interested in the use of electricity for urban transportation and proposed a major expansion of London's Underground in 1901.[6]

Sprague's system of electric supply was a great advantage in relation to the first bipolar U-tube overhead lines, in everyday use since 1883 on the Mödling and Hinterbrühl Tram.

Electric elevators

While electrifying the streetcars of Richmond, the increased passenger capacity and speed gave Sprague the notion that similar results could be achieved in vertical transportation — electric elevators. He saw that increasing the capacity of elevator shafts ways would not only save passengers' time, but would also increase the earnings of tall buildings, with height limited by the total floor space taken up in the shaftways by slow hydraulic-powered elevators.

In 1892, Sprague founded the Sprague Electric Elevator Company, and with Charles R. Pratt developed the Sprague-Pratt Electric Elevator. The company developed floor control, automatic elevators, acceleration control of car safeties and a number of freight elevators. The Spague-Pratt elevator ran faster and with larger loads than hydraulic or steam elevators, and 584 elevators had been installed worldwide. Sprague then sold his company to the Otis Elevator Company in 1895.

Multiple unit train controls

Sprague's experience with elevator control led him to devise a multiple unit system of electric railway operation, which accelerated the development of electric traction. In the multiple unit system, each car of the train carries electric traction motors. By means of relays energized by train-line wires, the engineer (or motorman) commands all of the traction motors in the train to act together. For lighter trains there is no need for locomotives, so every car in the train can generate revenue. Where locomotives are used, one person can control all of them.

Sprague's first multiple unit order was from the South Side Elevated Railroad (the first of several elevated railways locally known as the "L") in Chicago, Illinois. This success was quickly followed by substantial multiple-unit contracts in Brooklyn, New York and Boston, Massachusetts.

New York: Grand Central, elevators in skyscrapers

From 1896 to 1900 Sprague served on the Commission for Terminal Electrification of the New York Central Railroad, including the Grand Central Terminal in New York City, where he designed a system of automatic train control to ensure compliance with trackside signals. He founded the Sprague Safety Control & Signal Corporation to develop and build this system. Along with William J. Wilgus, he designed the Wilgus-Sprague bottom contact third rail system used by the railroads leading into Grand Central Terminal.[7]

During World War I, Sprague served on the Naval Consulting Board. Then, in the 1920s, he devised a method for safely running two independent elevators, local and express, in a single shaft, to conserve floor space. He sold this system, along with systems for activating elevator car safety systems when acceleration or speed became too great, to the Westinghouse Company.

Legacy and awards

The effect of Sprague's developments in electric traction was to permit an expansion in the size of cities, while his development of the elevator permitted greater concentration in cities' commercial sections and increased the profitability of commercial buildings. Sprague's inventions over 100 years ago made possible modern light rail and rapid transit systems which still function on the same principles today.

Sprague was awarded the gold medal In Paris at the International Exposition of Electricity in 1889, the grand prize at the St. Louis Exhibition in 1904, the Elliott Cresson Medal in 1904, the Edison Medal of the American Institute of Electrical Engineers (now Institute of Electrical and Electronics Engineers), in 1910 'For meritorious achievement in electrical science, engineering and arts as exemplified in his contributions thereto', the Franklin Medal in 1921 and the John Fritz Gold Medal (posthumously) in 1935.

"All through his life and up to his last day, Frank Sprague had a prodigious capacity for work", his son Robert wrote in 1935. "And once having made up his mind on a new invention or a new line of work, he was tireless and always striving for improvement. He had a brilliantly alert mind and was impatient of any half-way compromise. His interest in his work never ceased; only a few hours before the end, he asked to have a newly designed model of his latest invention brought to his bedside."

Frank and Harriet Sprague had three sons: Robert, Frank Desmond and Julian. Robert C. Sprague founded the Sprague Electric Company which became a leading manufacturer of capacitors and other electronic components. The company was later bought by Vishay Intertechnology in the 1990s.

After Sprague died in 1934, his widow Harriet turned over a substantial amount of material from his collection to the New York Public Library, where it remains today accessible to the public via the rare books division. He was buried at Arlington National Cemetery in Arlington, Virginia, and she was interred beside him after her death in 1969.

In 1959, Harriet Sprague had donated funds for the Sprague Building at the Shore Line Trolley Museum at East Haven, Connecticut, not far from Sprague's boyhood home in Milford. The museum is the oldest operating trolley museum in the United States, and has one of the largest collections of trolley artifacts in the United States.

In 1999, two of Frank and Harriet's grandsons, John L. Sprague and Peter Sprague, cut the ribbon and started an 1884 Sprague motor at a new exhibit at the Shore Line Trolley Museum. There, a permanent exhibit, "Frank J. Sprague: Inventor, Scientist, Engineer," helps tell the story of the part electricity played in the growth of cities as well as the role of the Father of Electric Traction. Entrepreneur Peter Sprague was Chairman of National Semiconductor from 1965 until 1995. Robert C. Sprague was President and Chief Executive Officer of Sprague Electric Company from 1981 to 1987.

Sprague's engines were used as far afield as Sydney Harbour, Australia. A five-horsepower Lundell electric motor used at the Cockatoo Island dockyard between 1900 and 1980 is now in the collection of the National Museum of Australia in Canberra.[8]

In 2012, the Pennsylvania Trolley Museum adopted a stray cat, naming it after Sprague: Frank the Trolley Cat.[9]


  1. 1 2 Demoro, Harre W. (1986). California's Electric Railways. Glendale, California: Interurban Press. p. 11. ISBN 0-916374-74-2.
  2. 1 2 "Biography: Frank J. Sprague". IEEE Global History Network. IEEE. Retrieved August 1, 2012.
  3. Kirby, Ed. "Inventor Frank Sprague" (PDF). Seldom Told Tales of Sharon (Book 3). Sharon, Connecticut: The Sharon Historical Society. Retrieved 8 May 2014.
  4. 1 2 Middleton, William D. (1967). The Time of the Trolley, pp. 63–73. Milwaukee: Kalmbach Publishing. ISBN 0-89024-013-2.
  5. 1 2 Cudahy, Brian J. (1972). Change at Park Street Under; The Story of Boston's Subways. Brattleboro, Vt.: S. Greene Press. ISBN 0-8289-0173-2.
  6. Sprague, Frank J. (October 1901). "The Rapid Transit Problem in London". The Engineering Magazine. XXIII (1).The article was reprinted at the time as a booklet, now scarce
  7. Cudahy, Brian (2003). A Century of Subways: Celebrating 100 Years of New York's Underground Railways. New York: Fordham University Press. p. 202. ISBN 0-8232-2292-6.
  8. "Five-horsepower Lundell electric motor with Sprague Electric plates.". National Museum of Australia. Retrieved August 14, 2015. Five-horsepower Lundell electric motor with "Sprague Electric Co. USA Lundell motor, pat. dates: Aug 30, 1892, Sept. 26, 1893, Aug 3 1897. No. 180 96 H Edge and Edge Sydney" on bronze plates
  9. Miller, Barbara S. (September 24, 2012). "Feline Frank top cat at trolley museum". Observer–Reporter. Archived from the original on September 25, 2012. Retrieved September 25, 2012.

Further reading

External links

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