These posing dudes are said to be painters on the Brooklyn Bridge, but I don't buy it. I think they're probably some kind of modern dance troupe. Just too well-arranged to be artisans.
The photo is by Eugene de Salignac, subject of a new book and an article in the Smithsonian magazine. Snippet:
It took many months and uncounted hours of trolling through archives storerooms, the Social Security index, Census reports and city records on births, deaths and employment to find the answer: the photographer was Eugene de Salignac, a municipal worker who took 20,000 photographs of modern Manhattan in the making. "It felt like a real discovery," Lorenzini says.
Still, what is known about de Salignac remains limited, and there are no known photographs of him as an adult. Born in Boston in 1861 and descended from French nobility, he married, fathered two children and, after separating from his wife in 1903, started working for the City of New York at age 42. He was the official photographer for the Department of Bridges from 1906 to 1934. At that point, his work—including original plate-glass negatives, corresponding logbooks in his elegant script and more than 100 volumes of vintage prints—began collecting dust in various basement storerooms. He died in 1943, at 82, unheralded.
But de Salignac is now having his day: the Museum of the City of New York is exhibiting his work through October 28, and Aperture has published a related book, New York Rises: Photographs by Eugene de Salignac, with essays by Lorenzini and photography scholar Kevin Moore.