Historian, born in Prussia; held a State office, but was dismissed and exiled because of his sympathy with the revolutionary movement of 1848; came to England to collect materials for a history of the Tudors; examined in Simancas, in Spain, under great privations, papers on the period in the public archives; made of these a collection and published it in 1862-68, under the title of "Calendar of Letters, Despatches, &c., relating to Negotiations between England and Spain" (1813-1869).