APRIL JLC 2000 BACKFILL Notes From the Underground Notes From the Underground by Jon Vara I took particular pleasure in this breaking of ground, for in almost all latitudes men dig into the earth for an equable temperature. The house is but a sort of porch at the entrance of a burrow. —Henry David Thoreau, Walden The island of Nantucket is home to some of the most expensive real estate this side of downtown Manhattan. Buildable land sells for about $6 million an acre, and a tworoom summer rental goes for several thousand a week. A good carpenter commands $70 an hour or more, but even at that wage scale, few can afford on-island accommodations. Many builders commute by air from nearby Cape Cod