2.  In 1946, the engineer Dr. Percy LeBaron Spencer, who worked for the Raytheon Corporation, was working on magnetrons. He saw that the microwaves he was working with had caused the chocolate bar to melt. He also realized that microwaves would cook foods quickly - even faster than conventional ovens that cook with heat. Its necessary because we can heat up our food faster and easier. Its effective in our world.  The American inventor Oliver Evans designed the first refrigeration machine in 1805. In 1844, John Gorrie, an American doctor from Florida made a device based on Evans' invention that would make ice in order to cool the air for yellow fever patients. They are necessary because they keep food cold. Its useful in their and our world because everybody needs a better way to keep food fresh and cold. And also to prevent from going bad

3. From 1910 to 1920, Oscar Minkowski and others tried unsuccessfully to find and extract the active ingredient from the islets of Langerhans. He realized that the pancreas' digestive juice was destroying the islets of Langerhans hormone before it could be isolated. If he could stop the pancreas from working, but keep the islets of Langerhans going, he should be able to find the stuff. This is necessary because it improved the world of medicine and science.  John Heysham Gibbon was born in Philadelphia, PA, and was a fourth generation physician. He was widely recognized for his pioneering efforts in surgery and the invention of the heart-lung bypass machine.

4.  In 1712, Thomas Newcomen and John Calley built their first steam engine on top of a water filled mine shaft and used it to pump water out of the mine. The Newcomen steam engine was the predecessor to the Watt steam engine and it was one of the most interesting pieces of technology developed during the 1700's. The invention of engines. The first being steam engines, was very important to the industrial revolution because it helped the water in the dams to stop the over flow or becoming over flow.steam engine  The first working airplane was invented, designed, made, and flown by the Wright brothers, Wilbur Wright and Orville Wright. Their "Wright Flyer" was a fabric-covered biplane with a wooden frame. Airplanes are necessary because they take you to point A and point B.

5.  The Telephone was invented on March 10, 1876. An instrument which converts sound, specifically the human voice, to electrical impulses of various frequencies and then back to a tone that sounds like the original voice. The inventor was Alexander Graham Bell. We need telephones today because its easier to reach people and easier contacted instead of mailing post cards jus to say something.

6.  The B-1B Lancer was first used in combat in support of operations against Iraq during Operation Desert Fox in December 1998. B-1s have been subsequently used in Operation Allied Force. The B-1B Lancer is the improved variant initiated by the Reagan administration in 1981. The first production model flew in October 1984, and the first B-1B was delivered to Dyess Air Force Base, Texas, in June 1985, with initial operational capability on Oct. 1, 1986. The final B-1B Lancer was delivered May 2, 1988. Its necessary because they help us the wars that we have today.  These sunglasses, created by the Japanese military, are designed to withstand an impact from an object 0.3 inches, traveling at 106 miles per hour. Not quite able to stop a bullet, but surely will save some soldier from loosing an eye to shrapnel. They can be necessary because they may actually work.