Part 1:
Necessity is the mother of invention, they say, and she has created some fairly unusual children. Animal Tracking-Satellites let scientist follow elephants, whales, and manatees. Baby Stretcher-When an infant is injured, this child-size stretcher provides more protection. Biodegradable Gold Tee-Take your swing, then leave the tee where it stands. Nature will do the rest. Boomerang-from Aboriginal weapon to child's toy, learn about the forces that bring boomerangs back. Velcro-the idea for this handy fastener came from a walk in a field thick with burrs.

Part 2:
Leonardo da Vinci-The Artist and inventor created-on paper, at least-the first helicopter. Galileo's Telescope-this Renaissance man risked all to discover the secrets of the spheres with his telescope. The wright Brothers-On a North Carolina beach, Orville and Wilbur wright took flight and made history. Lowell's Observatory-In his Arizona observatory, Percival Lowell looked to Mars for signs of life.