The collection of 300 glass plates made by the photographer of the Pacific Expedition, Rafael Castro y Ordóñez, is preserved in the Archives, together with the dispatches and documents relative to the expedition. These plates were in poor state in 1986, and dispersed throughout different locations in the Museum. The paper presented at this Symposium described the transfer of these plates to the Archives, and their restoration, financed by the Spanish Council for Scientific Research using a Special Effort fund. The result of these efforts was the recovery, publication, and exhibition of this extraordinary material in April 1992 at the Museo Nacional de Ciencias Naturales, as one of the projects of Madrid Cultural Capital.