Exhibition organizers talk about the development of Social Forces Visualized. A boy with leg braces and crutches rests against a fire alarm. A woman hangs laundry from a clothesline strung across an airshaft behind a row of tenement buildings. Pushcarts line a crowded street in lower Manhattan. These haunting black-and-white photographs are featured in a new exhibition at the Miriam and Ira D. Wallach Art Gallery that explores the role that social welfare organizations founded in the 19th and early 20th century played in documenting and alleviating the plight of the urban poor. Social Forces Visualized: Photography and Scientific Charity, 1900-1920 includes 125 photographs by such influential photographers as Jacob Riis, Lewis Hine and Jessie Tarbox Beals, who were hired by the charities to illustrate the overcrowded and unsanitary conditions in the slums of lower Manhattan. http://news.columbia.edu/oncampus/2598 Less