“At about 7 last night, ‘The Encampment,’ an installation of 100 19th-century-style tents by the Canadian artist Thom Sokoloski, was to open in an empty field at the southern tip of New York’s Roosevelt Island. A year in the making, the tents represent the patients who once lived in the island’s smallpox hospital, the remains of which loom nearby… But first, it had to be finished.”