DAVENPORT, THOMAS Thomas Davenport (July 9, 1802 -July 6, 1851) was an American blacksmith and inventor who established the first commercially successful electric streetcar. Davenport, from Vermont, invented an electric motor in 1834 and began a small electric railway in 1835. He patented a device for "Improvements in propelling machinery by magnetism and electromagnetism" in 1837 (his electric railway). Davenport later started a workshop in New York City, New York, and published a journal on electromagnetism (it was printed on a press that was powered by motors which he devised).

DA VINCI, LEONARDO Leonardo da Vinci (1452-1519) was an Italian inventor, artist, architect, and scientist. Da Vinci had an interest in engineering and made detailed sketches of the airplane, the helicopter (and other flying machines), the parachute, the submarine, the armored car, the ballista (a giant crossbow), rapid-fire guns, the centrifugal pump (designed to drain wet areas, like marshes), ball bearings, the worm gear (a set of gears in which many teeth make contact at once, reducing the strain on the teeth, allowing more pressure to be put on the mechanism), and many other incredible ideas that were centuries ahead of da Vinci's time.For some da Vinci art coloring pages, click here For more information on da Vinci, click here.

DAVY, HUMPHRY Sir Humphry Davy (1778-1829) was an English scientist who invented the first electric light in 1800. He experimented with electricity and invented an electric battery. When he connected wires from his battery to two pieces of carbon, electricity arced between the carbon pieces, producing an intense, hot, and short-lived light. This is called an electric arc. Davy also invented a miner's safety helmet and a process to desalinate sea water. Davy discovered the elements boron, sodium, aluminum (whose name he later changed to aluminium), and potassium.

DICKSON, EARLE Bandages for wounds had been around since ancient times, but an easy-to-use dressing with an adhesive was invented by Earle Dickson (a cotton buyer at the Johnson & Johnson company). Dickson perfected the BAND-AID® in 1920, making a small, sterile adhesive bandage for home use. Dickson invented the BAND-AID® for his wife, who had many kitchen accidents and needed an easy-to-use wound dressing. Dickson was rewarded by the Johnson & Johnson company by being made a vice-president of the company.

DIONYSIUS THE ELDER The catapult was invented in ancient Greece (in 399 BC) by Dionysius the Elder of Syracuse. The catapult is a device that hurls heavy objects or arrows over a large distance. The Romans later added wheels to the catapult to make it more maneuverable. Also called the ballista, this device was a major weapon of warfare for well over a thousand years. A double-armed catapult (also called the trebuchet) was invented by Mariano Taccola of Siena during the Middle Ages, about AD 1400.

DISHWASHER The first dishwasher was patented in 1850 by Joel Houghton; his machine was a hand-turned wheel that splashed water on dishes - unfortunately, it wasn't very effective at washing dishes. The first working automatic dishwasher was invented by Mrs. Josephine Garis (W. A.) Cochran, of Shelbyville, Illinois, in 1889. Her dishwasher was a wooden tub with a wire basket in it - the dishes went in the basket, and rollers rotated the dishes. As a handle on the tub was turned, hot, soapy water was sprayed into the tub, cleaning the dishes. Cochran's machine was first shown at the 1893 World's Fair in Chicago, Illinois. At first, her machine was only bought by some restaurants and hotels. Cochran's small company was eventually associated with the KitchenAid company. The dishwasher didn't become widespread as a labor-saving machine until the 1960s.

DISPOSABLE DIAPER The disposable diaper was invented in 1950 by Marion Donovan. Her first leak-proof diaper was a plastic-lined cloth diaper. Donovan then developed a disposable diaper. She was unsuccessful at selling her invention to established manufacturers, so she started her own company.

DONOVAN, MARION Marion Donovan (1917-1998) was an American mother, inventor, and architect who invented the disposable diaper in 1950. Her first leak-proof diaper were fast-selling "Boaters," plastic-lined cloth diapers (diapers lined with pieces cut from a shower curtain, and later with surplus parachute nylon). Donovan then developed a completely disposable diaper. She was unsuccessful at selling this invention to established manufacturers, so she started her own company, which she later sold. Donovan produced many other consumer-based inventions and held more than a dozen patents

DORTICUS, CLATONIA JOAQUIN Clatonia Joaquin Dorticus was an African-American inventor who received many patents. He invented an apparatus for applying dyes to the sides of the soles and heels of shoes (patent # 535,820, March 19, 1895), a machine for embossing (contouring the paper of) photographs (patent # 537,442, April 16, 1895), a device that helped develop photographs (patent # 537,968, April 23, 1895), and a leak stopper for hoses (patent # 629,315, July 18, 1899).

DOWNING, PHILIP B. The street letter drop mailbox with a hinged door that closed to protect the mail was invented by Philip B. Downing. Downing, an African-American inventor, patented his new device on October 27, 1891 (US Patent # 462,093).

DREW, CHARLES RICHARD Dr. Charles Richard Drew (1904-1950) was an American medical doctor and surgeon who started the idea of a blood bank and a system for the long-term preservation of blood plasma (he found that plasma kept longer than whole blood). His ideas revolutionized the medical profession and have saved many, many lives.For more information on Dr, C. R. Drew, click here.

DREW, RICHARD Richard G. Drew (1899-1980) invented masking tape and clear adhesive tape (also called cellophane tape or Scotch tape). Drew was an engineer for the 3M company (the Minnesota Mining and Manufacturing).Drew's first tape invention was a masking tape made for painters in 1923 (this tape was designed to help painters paint a straight border between two colors). This early masking tape was a wide paper tape with adhesive on only the edges of the tape - not in the middle. Drew made an improved tape called Scotch (TM) Brand Cellulose Tape in 1930. This tape was a clear, all-purpose adhesive tape that was soon adopted worldwide. The first tape dispenser with a built-in cutting edge was invented in 1932 by John A. Borden, another 3M employee.

DUTCH CHOCOLATE Coenraad Johannes Van Houten (1801-1887) was a Dutch chemist and chocolate manufacturer who in 1828 invented the process that is used to turn roasted cacao beans (the source of chocolate) into cocoa powder (this process is now called Dutching, Dutch processing or alkalinisation). His method was an inexpensive way of removing much of the cocoa butter from the nib (center) of the beans, using a hydraulic press, and adding alkaline salts (potassium carbonate or sodium carbonate) so that the cocoa powder would mix readily with water or milk (the alkali neutralized the acidic chocolate). The resulting cocoa powder can be used to make chocolate milk and other delicacies.