Playing with Caterpillars _ Machines, not Insects

 'My wife was a little dubious about my plans for a family day trip to the Caterpillar center, but my 4-year-old-son and I couldn't wait. My parents tell me my first word was "book" and my second word was "truck." I've been a big fan of both over the past four-plus decades. Now, with a little boy of my own, I had a perfect excuse to satisfy my mania for powerful engines, giant wheels, sturdy shovels and other nifty machines that dig, pound, push, flatten and otherwise manipulate materials in ways that seem beyond the strength of mere mortals. And I'm not alone: The center attracted 50,000 visitors within just four months of opening.'