Now here's a gadget with a real pedigree and a real story t. tell. You might recall its use in exciting demonstrations about energy transfer when you were at school. But the truth is, it's much, much more deeply interesting than all that. Invented in 1943 by naval engineer Richard James and first marketed in Philadelphia in 1945 - selling-out all 400 of its first run in just 90 minutes - the slinky was destined for greatness that has since taken it int. space on the Shuttle, t. war in Vietnam, and, yes, int. thousands of physics labs in schools across the world. Not only is it inspired in its invention (an accident), but it's equally inspired in terms of its brand name (the ramblings of a suburban housewife). Slinky. Brilliant. One just couldn't make it up. Now, as it approaches its 65th birthday, the slinky is Pennsylvania's official state toy. It has a guaranteed place in the official Toy Hall of Fame. Why? Because all you need is a slinky and a set of stairs, and a whole afternoon slips by. For sheer exuberant slink ability, there is only one original slinky. A 20th Century classic.