Gently, she swings back and forth — a dog in a birdcage. She is small and brown and angular, lean limbed and wasp-waisted; the birdcage is bamboo with its front removed, suspended from a slim, black pipe in this cluttered, poorly-lit basement. Although the arrangement is peculiar, the little dog seems comfortable, at home. Her continuous, rocking motion is almost hypnotic — but for the jarring scrape of metal on metal, hook slowly scoring pipe, and the fact that natural gas flows through the very pipe the birdcage trembles and grates against…