Scientists from Columbia, Cornell, Yale, Harvard, Union, Vassar and the United States Geological Survey participated in the fourth annual exhibition of the New York Academy of Sciences, at the American Museum of Natural History. A highlight of the exhibit was the device perfected over many years by Professor of Geology William Buck Dwight for preparing transparently thin specimens of rocks and fossils.  Using a series of tin discs edged with diamond dust, Dwight was able to prepare consecutive parallel slices of geological materials up to eight inches in diameter to a thickness of one fiftieth of an inch.