John Farquhar has been described as "a tailor's cutter of very limited means" (Kilburn & Rippey, 1982, p. 19). He was a Scotish naturalist living in Port Elizabeth, where he joined the Eastern Province Naturalists' Society in June 1883. (The society was founded in 1882 as the Port Elizabeth Naturalists' Society and renamed two years later). He regularly exhibited natural history specimens at its meetings, for example, insects and shells in April 1884, more shells in September, a large collection of shells, crustaceans, minerals, fishes and fossils at a conversazione in December 1884, and birds and shells in February 1887. At the latter meeting his wife exhibited hydrozoa. He was elected a member of the society's committee in January 1887 and re-elected annually for the next four years. He also served on the committee of management of the Port Elizabeth Museum in 1888 and donated many shells to its collections in that year and the next.
At some time during the 1890s Farquhar moved to Grahamstown and in 1898 presented nine molluscs from various places in South Africa to the Albany Museum. In addition to marine shells he also collected land snails, exchanging specimens and observations with H.C. Burnup* of Pietermaritzburg. In 1912 he presented a small but valuable collection of minute land snails collected in the neighbourhood of Grahamstown to Albany Museum, followed by several more species the next year. During later years his interest turned also to raised beaches. For example, in 1906 he and E.G. Bryant* of Port Elizabeth presented to Albany Museum a collection of shells from raised beaches in the Port Elizabeth area, some as much as 450 m above present sea level. These were to be used by the geologist E.H.L. Schwarz* to study changes in sea level. Farquhar also donated palaeozoic fossils from Scotland in 1906 and 1907, and helped the museum with the identification of its younger fossils in 1909. He bequeathed his shell collection to the museum, from where it was later transferred to the Natal Museum. Several species of shells were named after him and though some of these have since been renamed, the land snails Nesopupa farquhari, Gulella farquhari and Afrodonta farquhari still carry his name.