“A dog’s nervous system is in a class by itself,” wrote E. B. White in a 1939 essay. “If it resembles anything at all, it resembles the Consolidated Edison Company’s power plant.” As it happens, a decade later White began Here is New York, his exposition on the great metropolis, by referring to its gifts “of loneliness” and “privacy.” Gifts to some, yes. Others become fairly distressed by the isolating effect of the big city, and for them the prescription is simple: acquire a companion animal with the nervous system of a power plant. Take a walk through Central Park, and you’ll see this antidote in action. An exhibition at the New-York Historical Society features art, objects, memorabilia, and film and television clips that demonstrate the tenured presence of pets in the five boroughs. —Jack Sullivan