Inspector-General Belgrave Ninnis CVO FRGS FSA (1 September 1837 – 18 June 1922) was a Royal Navy surgeon, surveyor, Arctic explorer, and leading Freemason, from London.

He received Sir Gilbert Blane's gold medal in 1879, was promoted to Deputy Inspector-General in 1883, was appointed Principal Medical Officer at Melville Naval Hospital in 1892, and was selected as a Knight of Grace of the Venerable Order of Saint John in 1895.

Upon his retirement in 1897 he was promoted to Inspector-General, and in 1900 and 1902 served as President of the Section of the Navy, Army, and Ambulance of the British Medical Association.

Ninnis graduated from the University of St Andrews as a Doctor of Medicine on 2 January 1861, and became a Member of the Royal College of Surgeons—MCRS; a professional qualification—in April of the same year.

[4] The expedition, under Boyle Travers Finniss, was charged with surveying the coast in the area of the Adelaide River, with the aim of selecting a site for a future territory capital.

[10][11] Ninnis later reported to the Adelaide Philosophical Society on geological findings; "the coast at the Northern Territory," he said, "was generally composed of red and grey sandstone, with small quantities of quartz.

[4] His research on the expedition later formed the basis of a published work, Remarks on the Natural History, Meteorology, and Native Population of Northern Australia.

He collected wheat seeds left in the area by the Polaris expedition four years previously, and planted them—together with mustard, cress and pea seeds—between the decks of the Discovery.

According to Robert Johnston, in his 1877 summary of the expedition, "This experiment succeeded very well; but, evidently, such an attempt at fancy gardening, under difficulties, could not be relied on to supply the wants of an entire ship's crew.

[3] He was appointed Principal Medical Officer at Melville Naval Hospital, Chatham in 1892, and three years later was selected as a Knight of Grace to the Venerable Order of Saint John.

In the address, while arguing that light and fresh air were important for the treatment of wounded sailors, noted that they could "only be obtained in sufficient quantity above the water-line, and to place the sick quarters above the water-line, amidst the hurly-burly of a sea fight, traversed by projectiles and wrecked by exploding shells, is of course out of the question, even supposing that sufficient space could be spared.

"[30] Instead, he argued for dedicated hospital ships, which "during an action ... would keep out of range but sufficiently close to collect the wounded when the fight was over, and sailing under the regulations of the Geneva Convention would be free from molestation or capture.

Along with Mawson and Xavier Mertz, he formed the Far Eastern Party, using sledge dogs to explore the area around the expedition's base in Adélie Land.

[46] When news of his death reached Australia in March 1913, several Australian newspapers—including The Advertiser, the Western Argus and The Sydney Morning Herald—ran biographies of Belgrave Ninnis, noting his surveying work in the Northern Territory and Arctic exploration.

[nb 3][42][47][48] When Mawson returned to Australia a year later, a telegram was sent on behalf of the Australian people to Ninnis senior, condoling him on his "great loss, but congratulating you on your son's imperishable fame.