The borough of Narberth embraces the Fourth of July like sparks on a fuse, and by this time of year signs of the holiday pop up everywhere, including the window of Narberth Pharmacy in the heart of downtown. That evening the town’s population more than doubles as a throng collects in the park for a program that starts at 7:30 p.m. and culminates with the fireworks show that begins at dusk, usually about 9:15 p.m.