INCANDESCENT LIGHT BULB The first incandescent electric light was made in 1800 by Humphry Davy, an English scientist. He experimented with electricity and invented an electric battery. When he connected wires to his battery and a piece of carbon, the carbon glowed, producing light. This is called an electric arc.Much later, in 1860, the English physicist Sir Joseph Wilson Swan (1828-1914) was determined to devise a practical, long-lasting electric light. He found that a carbon paper filament worked well, but burned up quickly. In 1878, he demonstrated his new electric lamps in Newcastle, England. The inventor Thomas Alva Edison (in the USA) experimented with thousands of different filaments to find just the right materials to glow well and be long-lasting. In 1879, Edison discovered that a carbon filament in an oxygen-free bulb glowed but did not burn up for 40 hours. Edison eventually produced a bulb that could glow for over 1500 hours. The incandescent bulb revolutionized the world. For more information, click here.

INTEGRATED CIRCUIT An integrated circuit (IC) or chip is a wafer of material to which impurities have been added (in just the right patterns) so that the entire chip is a circuit composed of many transistors. The chip (usually made of silicon or germanium) makes computational devices, like computers, very small and very inexpensive. IC's were invented independently in 1959 by Jack Kilby and Robert Noyce.

INTERCHANGEABLE PARTS Clock makers used the idea of interchangeable parts since the early 1700's. In 1790, the French gunsmith Honoré Blanc demonstrated his muskets entirely made from interchangeable parts; the French government didn't like the process (since with this process, anyone could manufacture items, and the government lost control), so it was stopped. The idea of interchangeable parts was introduced to American gun manufacturing by Eli Whitney (1765-1825) in 1798. The concept of interchangeable manufacturing parts helped modernize the musket industry (and mass production in general). Whitney made templates for each separate part of the musket (an early gun). The workers then used the template when chiseling the part. Whitney was an American inventor and engineer who also invented the cotton gin.

IRON, ELECTRIC The electric iron was invented in 1882 by Henry W. Seeley, a New York inventor Seeley patented his "electric flatiron" on June 6, 1882 (patent no. 259,054). His iron weighed almost 15 pounds and took a long time to warm up.Other electric irons had also been invented, including one from France (1882), but it used a carbon arc to heat the iron, a method which was dangerous.