 At the age of thirteen he joined the flagship of Admiral Sir William Cornwallis in the Channel fleet as a first-class volunteer, in 1806 became a midshipman, and in 1810 received promotion to the rank of lieutenant in the frigate "Alexander", which spent the next three years in the protection of the Spitsbergen whale fishery.Parry took advantage of this opportunity for the study and practice of astronomical observations in northern latitudes, and afterwards published the results of his studies in a small volume on "Nautical Astronomy by Night".From 1813 to 1817 he served on the North American station.