Background
John Gwyn Jeffreys was born on January 18, 1809, in Swansea, Wales. He was the eldest son of John Jeffreys, a solicitor.
De-La-Beche Rd, Sketty, Swansea SA2 9AP, Wales
Jeffreys was educated in Swansea at the Bishop Gore School (Swansea Grammar School).
Jeffreys in Dublin.
A portrait of Jeffreys.
Jeffreys c. 1855.
A photo of Jeffreys.
De-La-Beche Rd, Sketty, Swansea SA2 9AP, Wales
Jeffreys was educated in Swansea at the Bishop Gore School (Swansea Grammar School).
Jeffreys in Dublin.
A portrait of Jeffreys.
Jeffreys c. 1855.
A photo of Jeffreys.
https://www.amazon.com/British-conchology-account-Mollusca-inhabit/dp/1116805111/?tag=2022091-20
1862
https://www.amazon.com/report-dredging-among-Shetland-Isles/dp/B0080FRQUO/?tag=2022091-20
1868
https://www.amazon.com/depths-sea-dredging-Porcupine-Lightning/dp/B00AL6NZPA/?tag=2022091-20
1873
malacologist scientist Zoologist conchologist
John Gwyn Jeffreys was born on January 18, 1809, in Swansea, Wales. He was the eldest son of John Jeffreys, a solicitor.
Jeffreys was educated in Swansea at the Bishop Gore School (Swansea Grammar School). He was articled to a solicitor at seventeen but, as his tastes were scientific rather than legal, he spent his holidays dredging from a rowboat in Swansea Bay. He qualified as a barrister in 1838.
Jeffreys practiced as a solicitor until 1856, when he was called to the bar at Lincoln’s Inn. Although he could spare only short holidays, each summer from 1861 to 1868 was spent dredging, mostly to the north and west of Scotland. In 1866 he retired from the legal profession to devote all his time to the study of the European Mollusca. His discoveries early led him to suspect that the present-day malacofauna is directly descended from that of the late Tertiary deposits, as he found many crag mollusks, formerly supposed to be extinct, still living in the seas around Shetland and the Hebrides. After publishing numerous short papers on the results of his explorations, Jeffreys brought out a five-volume systematic treatise, British Conchology.
In 1843 Edward Forbes had postulated that no life would be found in the sea below a limit of about 300 fathoms. This was still generally believed in the 1860s, although by then enough evidence had already come to light to have made the hypothesis no longer tenable. In 1868 a successful haul had been made from 650 fathoms during the experimental cruise of H.M.S Lightning, demonstrating the possibility of exploring depths rather greater than the 200 fathoms to which most previous dredging had been confined. That cruise also cast doubt on the then current belief that the temperature of seawater is a constant 4°C. below a certain depth. In 1869 and 1870 the Admiralty survey ship Porcupine was made available for further oceanographic investigations, and Jeffreys was given charge of the scientific work on two of her cruises.
A great number of new species, especially of mollusks, were collected, with others previously known only as Tertiary fossils. The dredge was successfully worked to a maximum depth of 2,435 fathoms and life was found to be present at all levels. The existence of cold-water and warm-water areas in close proximity at similar depths was also confirmed. Thus two prevalent ideas - the azoic zone and the universal minimum temperature - were shown conclusively to be false. From a conchological point of view, the cruises of the Lightning and Porcupine yielded considerably more material than the subsequent and much more extensive voyage of the Challenger; and the mollusks obtained occupied Jeffreys for the rest of his life.
In 1875 he superintended the deep-sea explorations of H.M.S. Valorous, which accompanied the Arctic expedition of Captain Sir George S. Narcs as far as Baffin Bay; and in 1880, by invitation of the French government, he took part in dredging the deep water of the Bay of Biscay on board the Travailleur. This was Jeffreys' last active participation in marine research.
His collection was unrivaled for British mollusks and also contained a very extensive series of Mediterranean, Scandinavian, and Arctic species. His exact knowledge of recent European mollusks made his opinions on those of the late Tertiary deposits of particular value, and the latter too were well represented in his collection. Jeffreys' collection was intended for the British Museum but, as a result of a disagreement with those in authority there, it was sold to the Smithsonian Institution for a thousand guineas a few years before Jeffreys' death.
John Gwyn Jeffreys is remembered as a distinguished zoologist who contributed greatly to the development of malacology and conchology. His treatise, British Conchology, remains a standard work of reference on the subject to this day; the species Rissoella opalina, Cima minima, and Cheirodonta pallescens were first scientifically described by him.
His collection of shells and specimens was partly donated to the National Museum of Natural History in Washington.
In 1840 he received an honorary Doctor of Law degree from St. Andrews University.
Jeffreys appreciated more than any conchologist before him the necessity for careful comparison with good series and actual specimens of types. For this purpose, he visited all the principal European collections and added extensively to his personal collection by exchange and purchase.
In 1827 Jeffreys was elected a fellow of the Linnean Society. In 1840 he was elected a fellow of the Royal Society. He was also a fellow of the Geological Society of London. In 1884 he was one of the founders of the Marine Biological Association of the United Kingdom.
Jeffreys was throughout his life a most indefatigable worker, and at time of his death was still actively engaged upon the description of the deep-sea mollusca dredged by the Lightning and the Porcupine expeditions.
In 1840 Jeffreys married Anne Nevill. They had a son and four daughters and also were the grandparents of the physicist Henry Gwyn Jeffreys Moseley.
