- Apr 3 Leon Michel Gambetta, French attorney and 37th Prime Minister of France (1881-82), born in Cahors, Kingdom of France (d. 1882)
- Apr 5 Alpheus Hyatt, American zoologist and paleontologist, born in Washington, D.C. (d. 1902)
- Apr 11 Joseph Leopold Röckel, German-British composer, music publisher, and teacher, born in London, England (d. 1908)
John Muir (1838-1914)
Apr 21 Scottish naturalist and discoverer (glaciers in High Seirras), born in Dunbar