I visited my friend Jay at work today, cleaned house, and solved a mystery, all in one fell swoop. He works for The (Cambridge Dept. of Public) Works, at their Recycling Center, a mere three blocks from my house. I’d never seen it before, and I’ve got to say, it has pretty poor visibility. But they take pretty much everything, from your run-of-the-mill recycling like paper and plastic to packing peanuts, corrugated cardboard, appliances, computers, and books, which are re-distributed via their book exchange shelves, perhaps the most popular of their many services. In the parking lot in front of the drop-off center, I watched as cops in marked and unmarked cars filled up at an otherwise unattended set of pumps, answering once and for all the question ‘where do cops get gas?’