On a hot mid-summer morning, Washington Cemetery in Brooklyn is blazing. Shadeless and weedy, it is occupied mostly by dragonflies and mockingbirds, along with a smattering of Italian wall lizards whose ancestors, according to legend, escaped from a pet store delivery truck in the Bronx back in the 1960s.

The heat has them basking on tombstones, as if they were back in Tuscany, and they skitter away as I come walking through with Michael Hirsch, a genealogist and historian who has made it his mission to care for the graves of the victims of the Triangle Shirtwaist Factory fire. It was the end of the workday on Saturday, March 25, 1911, when someone dropped a cigarette butt, or maybe a lit match, into a bin of scraps and sparked a fire on the eighth floor of the Asch Building near Washington Square.