John Ferrier was appointed assistant surgeon on the brig Royalist on 12 December 1832. He was appointed surgeon to the Survey vessel Thunder in 27 July 1841 (North America and West Indies) 
John Ferrier was employed as Surgeon-Superintendent on the convict ship Earl Grey to Van Diemen's Land in 1850. The Earl Grey departed Dublin, Ireland on 17 December 1849 with 240 female convicts and arrived in Hobart on 9 May 1850.
He was appointed to the Flag Ship H.M.S. Impregnable in May 1851  He died at the Royal Naval Hospital in 1852 while still in service on H.M.S. Impregnable. 
He left his entire estate to his niece Margaret Bonnar. 
Notes and Links
1). National Archives. Reference: ADM 101/21/5 Description: Medical journal of the Earl Grey, convict ship, from 1 December 1849 to 22 May 1850 by John Ferrier, Surgeon RN, during which time the said ship was employed in transporting convicts to Hobart Town.