By seven on an August evening the heat lets go of Berwick's side streets and the maples throw long shade across the lawns. Langley Mowing takes care of those yards — cutting, string trimming, edging along walks and drives, and clearing the leaves down when the maples finally let go. A tight edge along a granite curb is a small thing to be proud of, and it shows from the road. Grass in this town grows thick and comes back quickly, so the rhythm is steady and the schedule is kept. Berwick lawns and the ones nearby, week in and week out.