A Slinky, or "Lazy-Spring," is a coil-shaped toy invented by mechanical engineer Richard James in Philadelphia, Pennsylvania.
Slinkys come in various sizes. The shape is a simple helix, or coil design, of a ribbon of material, originally metal. The Slinky can "walk" down stairs as the coils stretch and reform as gravity moves them down each step.
In 1943, Richard James, and his assistant Coleman Barber, a US $50,000-a-year marine engineer stationed at the Cramp shipyards in Philadelphia, observed a torsion spring fall off a table and roll around on the deck (a torsion spring has no compression or tension). He told his wife: "I think there could be a toy in this." With a US$500 loan, the couple ran tests, experimented with materials, and produced four hundred units of the toy. Betty James did some dictionary searching and came up with the name "Slinky".
The earliest toys were made from materials found in nature, such as rocks, sticks, and clay. Thousands of years ago, Egyptian children played with dolls that had wigs and movable limbs which were made from stone, pottery, and wood. In Ancient Greece and Ancient Rome, children played with dolls made of wax or terra cotta, sticks, bows and arrows, and yo-yos. When Greek children, especially girls, came of age it was customary for them to sacrifice the toys of their childhood to the gods. On the eve of their wedding, young girls around fourteen would offer their dolls in a temple as a rite of passage into adulthood.
As technology changed and civilization progressed, toys also changed. Whereas ancient toys were made from materials found in nature like stone, wood, and grass modern toys are often made from plastic, cloth, and synthentic materials. Ancient toys were often made by the parents and family of the children who used them, or by the children themselves. Modern toys, in contrast, are often mass-produced and sold in stores.
This change in the nature of toys is exemplified by the changes that have taken place in one of the oldest and most universal of human toys; dolls. The earliest and most primitive dolls were simple wooden carvings and bundles of grass. Egyptian dolls were sometimes jointed so that their limbs could move realistically. By the early 1800s there were dolls that could say "mama". Today there are dolls that can recognize and identify objects, the voice of their owner, and choose among hundreds of pre-programed phrases with which to respond. The materials that toys are made from have changed, what toys can do has changed, but the fact that children play with toys has not changed.