Master, in the royal navy, was an officer ranking with, but junior to, lieutenants, and charged with the details of sailing the vessel, under the general orders of the captain. In recent years the title has been changed to 'navigating lieutenant.' In the merchant navy the master of a vessel, usually, by courtesy, denominated the captain, is the officer commanding her.
Master
Chambers's Encyclopaedia, Volume 7: Maltebrun to Pearson, p. 86
Source scan(s): p. 0095