Thomas Davenport biography
Date of birth : 1802-07-09
Date of death : 1851-07-06
Birthplace : Williamstown, Vermont
Nationality : American
Category : Science and Technology
Last modified : 2010-06-03
Credited as : Scientist and inventor, Inventor of the first DC electrical motor,
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Thomas Davenport from a daguerreotype of about 1850 reprinted from Franklin Leonard Pope, “The Inventors of the Electric Motor”, The Electrical Engineer 11 (7 January 1891) 3.
Thomas Davenport was born in 1802 in Vermont on a farm outside Williamstown, Vt., the eighth of 12 children. His father died when Thomas was 10. Schooling opportunities were minimal, and at the age of 14 Thomas was indentured for seven years to a blacksmith. His room and board and six weeks per year of rural schooling were provided in return for service in his master’s shop. The work was hard, but the boy was later remembered for his curiosity, his interest in musical instruments, and his passion for books.
Once he was liberated in 1823, Davenport traveled over the Green Mountains to Forestdale, a hamlet in the town of Brandon, Vt., where there was an iron industry. He set up his own marginally successful shop, married Emily, a daughter of Rufus Goss, a local merchant, and started a family.
His only means of learning was self-education. When the news from the ironworks piqued his curiosity, he acquired books and journals, and started reading about the experiments and discoveries that were beginning to unlock some of the mysteries of electricity and magnetism.
In the spring of 1833 Thomas Davenport heard some curious news. This news, as it turned out, would not only change his life but would eventually change the life of almost everyone on earth. The momentous news that roused the blacksmith’s curiosity was that the Penfield and Hammond Iron Works, on the other side of Lake Champlain in the Crown Point hamlet of Ironville in New York state, was using a new method for separating crushed ore.
The process used magnetized spikes mounted on a rotating wooden drum that attracted the millings with the highest iron content. Higher-purity feedstock could be fed to the furnaces, improving their productivity and the quality of the iron they produced. This was important, since the recent introduction and expected rapid expansion of railroads were dramatically increasing the demand for quality iron.
This process had been developed by Joseph Henry of Albany, N.Y. It used an electromagnet that he had designed to magnetize the spikes; in fact, Henry’s electromagnet was said to be powerful enough to lift a blacksmith’s anvil. Its use in the iron ore separation process was the first time that electricity had been used for commercial purposes, thus beginning the electric industry. Thomas Davenport had no prior knowledge of discoveries in magnetism and electricity when this new process stimulated his interest.
Soon after he learned of the Henry magnet, Davenport traveled the 25 miles to Crown Point on a horse to witness the wonders of magnetic lifting power. The amazing sight further inflamed his interest. He decided to travel another 80 miles south, to Albany, to meet Henry, only to find out that he had moved down to Princeton. Returning home out of money, Davenport called upon his brother, a peddler, to join him with his cart for another trip to Crown Point. Once there, they auctioned the brother’s products and traded a good horse for an inferior one to obtain money to buy the magnet. When they got home, the brother suggested trying to recover the cost by exhibiting the magnet for a fee.
Thomas Davenport had other plans. He unwound and dismantled the magnet as his wife, Emily, took notes on its method of construction. He then started his own experiments and built two more magnets of his own design. Insulated wire was required, but only bare wire was available. Emily Davenport cut up her wedding dress into strips of silk to provide the necessary insulation that allowed for the maximum number of windings.
The electricity source for the magnets was a galvanic battery of the type developed by Volta. It used a bucket of a weak acid for an electrolyte. The bucket contained concentric cylinders of different metals for electrodes; these were wired to provide external electric current to the magnet.
Davenport mounted one magnet on a wheel; the other magnet was fixed to a stationary frame. The interaction between the two magnets caused the rotor to turn half a revolution. He learned that by reversing the wires to one of the magnets he could get the rotor to complete another half-turn. Davenport then devised what we now call a brush and commutator. Fixed wires from the frame supplied current to a segmented conductor that supplied current to the rotor-mounted electromagnet. This provided an automatic reversal of the polarity of the rotor-mounted magnet twice per rotation, resulting in continuous rotation.
The motor had the potential to drive some of the equipment in Davenport’s shop, but he had even bigger ideas. The era of the steam locomotive and railroads was just beginning, but already boiler failures and explosions were becoming frequent, tragic occurrences. Davenport’s solution was the electric locomotive. He built a model electric train that operated on a circular track 4 feet in diameter; power was supplied from a stationary battery to the moving electric locomotive using the rails as conductors to transmit the electricity.
When Davenport traveled to Washington to obtain a patent, however, his application was rejected: There were no prior patents on electric equipment. He started a tour of colleges to meet professors of natural philosophy who might examine his invention and provide letters of support to the patent office. His travels took him to the new Rensselaer Institute in Troy, N.Y., recently founded (in 1824) as the nation’s first engineering school by Stephen Van Rensselaer.
The last of eight generations of land-owning patroons, Van Rensselaer had been a commissioner overseeing the construction of the Erie and Champlain canals, opened in 1825. The school had been charged with a mission to qualify teachers for instructing the sons and daughters of farmers and mechanics in developing methods of applying science to the common purposes of life.
Davenport met Rensselaer’s founding president, Amos Eaton, a distinguished lawyer, botanist, geologist, chemist, educator, and innovator, who was amazed by the motor and by the self-educated blacksmith who had built it. Eaton arranged an additional exhibit for the citizens of Troy, and Stephen Van Rensselaer himself bought Davenport’s motor for the school. The nation’s first engineering school now possessed the world’s first electric motor.
After refining the machine, Davenport and Smalley (Davenport’s friend and assistant) demonstrated their “electromagnetic engine” to Professor Turner of Middlebury College at Middlebury, Vermont, in December of 1834. In a handwritten note of January 5, 1835, Professor Turner described “Davenport and Smalley’s Specification of their Invention of an Electro-Magnetic Machine.” His description of the invention was illustrated with the drawing shown here.
With the sale of his motor, Davenport was able to buy a quantity of already insulated wire, and he returned home to build another motor. He traveled to Princeton to meet Joseph Henry and then to the University of Pennsylvania to meet Professor Benjamin Franklin Bache, Benjamin Franklin’s grandson and an outstanding scientist.
The self-educated blacksmith, having now impressed the most prominent men of learning in the country, returned to the patent office with letters and a working model. His troubles were not yet over, however. The model was destroyed by fire before it was examined. He built another and tried again. At last, the first patent on any electric machine was issued to Thomas Davenport for his electric motor on February 25, 1837.
A page with the drawings from the Davenport’ patent of February 25, 1837.
The scientific community and the media responded with great excitement and high expectations. Benjamin Silliman, the founder of Silliman’s Journal of Science, wrote an extended article and concluded that a power of great but unknown energy had unexpectedly been placed in mankind’s hands. The New York Herald proclaimed a revolution of philosophy, science, art, and civilization: “The occult and mysterious principle of magnetism is being displayed in all of its magnificence and energy as Mr. Davenport runs his wheel.”
Davenport set up a laboratory and workshop near Wall Street in hopes of attracting investors. Samuel Morse, who in 1844 would commercialize the telegraph, came to observe. To further advertise his motor, Davenport established his own newspaper, “The Electro-Magnet and Mechanics Intelligencer”, and used his electric motor to drive his rotary printing press.
The motor was a spectacular technological success, but it was becoming a commercial failure. No one knew how to predict the amount of energy in chemical batteries, and a battery-powered motor could not compete with a steam engine. Funds were promised but not delivered. Bankrupt and distressed, Davenport returned to Vermont and started writing a book describing his work and his vision for his electric motor. He died in 1851 just three days before his 49th birthday, leaving only a prospectus.
What Davenport could not anticipate, and what no one else would describe for another 20 years, was that his motor would be turned by water or steam power and would operate in reverse, as an electric generator. Within 40 years of his death, electric-powered trains and trolleys had become common, with Davenport’s machine creating electricity at the power station and his motor then converting this electricity back to mechanical power to move the cars. In 1882, his Pearl Street station in lower Manhattan used steam engines to drive shunt-wound brush and commutator dc generators of the type that Thomas Davenport had invented 45 years earlier. Recognizing that expanding demand would require a massive new manufacturing and service industry, Edison started a manufacturing facility in Schenectady that would become the General Electric Co. The company’s first products were motors and generators that copied the design and principles of Thomas Davenport’s motor.
Davenport the blacksmith was a bridge between the age of muscle power and the new era of electrical machinery. Not only were his inventions significant, but he was among the first to recognize that electricity would change everything. He deserves to be remembered as one of the great leaders of modern technology.
Interest in the achievements of Thomas Davenport grew during the late 1890s and early 1900s as the significance of the electric motor finally became generally recognized. The Vermont Electrical Association and the National Electric Light Association observed “Davenport Day” on September 28, 1910, in conjunction with the Vermont Historical Association. A large marble block with a bronze plaque commemorating Thomas Davenport was unveiled at the celebration.
Thomas Davenport died on July 6, 1851 , Salisbury, Vt., U.S.A.
In 1929, Rev. Walter Rice Davenport, nephew of Thomas Davenport, wrote the Biography of Thomas Davenport, “The Brandon Blacksmith, Inventor of the Electric Motor”, which was published by the Vermont Historical Society. The book presents a sentimental account of Thomas Davenport’s life, based largely on an autobiographical manuscript written by Thomas Davenport in 1849.
