Magnetic chart of the Indian Ocean - Imray, James F. (James Frederick), 1829?-1891.; Imray, James F. (James Frederick), 1829?-1891.; Jenkins, Henry D. (Henry Davenport); James Imray and Son. (London : James Imray & Son, 1886)
Map of the Indian Ocean showing lines of equal magnetic variation.
Plate [1] on leaf before title page in: Indian Ocean pilot : the seaman's guide to the navigation of the Indian Ocean, with numerous illustrations, charts and plans / by J. F. Imray & H. D. Jenkins ; to which is added Notes on the Physical geography of the Indian Ocean by W. H. Rosser. London : James Imray & Son, 1886.