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| Sponsor | Royal Society of London,Royal Navy |
|---|---|
| Country | United Kingdom |
| Leader | CaptainGeorge Nares |
| Start | Portsmouth, England 21 December 1872 (1872-12-21) |
| End | Spithead, England 24 May 1876 (1876-05-24) |
| Ships | HMSChallenger |
| Crew | 237 (21 officers, 216 crew) |
| Survivors | 144 |
| Route | |
 Track of HMSChallenger from December 1872 until May 1876. The colour contours represent ocean surface density. | |
TheChallenger expedition of 1872–1876 was a scientific programme that made many discoveries to lay the foundation ofoceanography. The expedition was named after the naval vessel that undertook the trip,HMS Challenger.
The expedition, initiated byWilliam Benjamin Carpenter, was placed under the scientific supervision of SirCharles Wyville Thomson—of theUniversity of Edinburgh andMerchiston Castle School—assisted by five other scientists, including SirJohn Murray, a secretary-artist and a photographer.[1] TheRoyal Society of London obtained the use ofChallenger from theRoyal Navy and in 1872 modified the ship for scientific tasks atSheerness,[2] equipping it with separate laboratories fornatural history andchemistry. The expedition, led by CaptainGeorge Nares, sailed fromPortsmouth, England, on 21 December 1872.[3] Other naval officers included CommanderJohn Maclear.[4][1]
Under the scientific supervision of Thomson himself, the ship travelled approximately 68,890 nautical miles (79,280 miles; 127,580 kilometres) surveying and exploring.[5] The result was theReport of the Scientific Results of the Exploring Voyage of H.M.S. Challenger during the years 1873–76 which, among many other discoveries, catalogued over 4,000 previously unknown species. John Murray, who supervised the publication, described the report as "the greatest advance in the knowledge of our planet since the celebrated discoveries of the fifteenth and sixteenth centuries". The report is available online as theReport of the Voyage of HMS Challenger.Challenger sailed close toAntarctica, but not within sight of it.[6][1] However, it was the first scientific expedition to take pictures of icebergs.[1]
The expedition, which circumnavigated the Earth, collected data by lowering sounding lines to the bottom of the ocean floor to measure its depth and collect sediment samples, by collecting marine organisms by means of dredges lowered to the ocean floor and trawls lowered into the water at different depths, by measuring temperature at various depths and by collecting samples of seawater at standard depths for chemical analysis.[7] They collected plankton samples and recorded the speed and direction of ocean surface currents. Samples were preserved in brine or alcohol, or dried, then brought to Europe and distributed to various experts to analyse.
To enable it to probe the depths, 15 ofChallenger's 17 guns were removed and its spars reduced to make more space available. Laboratories, extra cabins and a specialdredging platform were installed.[8]Challenger used mainly sail power during the expedition; the steam engine was used only for dragging the dredge, station-keeping while taking soundings, and entering and leaving ports.[8] It was loaded with specimen jars, filled with alcohol for preservation of samples, microscopes and chemical apparatus, trawls and dredges, thermometers, barometers, water sampling bottles,sounding leads, devices to collect sediment from the sea bed and great lengths of rope with which to suspend the equipment into the ocean depths.[9]
Because of the novelty of the expedition, some of the equipment was invented or specially modified for the occasion. It carried 181 miles (291 km) of Italianhemp rope forsounding.[10]
On its landmark journey circumnavigating the globe,[3] 492 deep sea soundings, 133 bottom dredges, 151 open water trawls and 263 serial water temperature observations were taken.[11][1] About 4,700 new species of marine life were discovered.
The scientific work was conducted byWyville Thomson,John Murray,John Young Buchanan,Henry Nottidge Moseley andRudolf von Willemoes-Suhm. Frank Evers Bed was appointedprosector. The official expedition artist wasJohn James Wild.[4] As well as Nares and Maclear, others that were part of the naval crew includedPelham Aldrich, George Granville Campbell and Andrew Francis Balfour (one of the sons of Scottish botanistJohn Hutton Balfour).[4] Also among the officers wasThomas Henry Tizard, who had carried out important hydrographic observations on previous voyages. Though he was not among the civilian scientific staff, Tizard would later help write the official account of the expedition, and also become aFellow of the Royal Society.
The original ship's complement included 21 officers and around 216 crew members.[8] By the end of the voyage, this had been reduced to 144 due to deaths, desertions, personnel being left ashore due to illness, and planned departures.[8]
Challenger reachedHong Kong in December 1874, at which point Nares and Aldrich left the ship to take part in theBritish Arctic Expedition. The new captain was Frank Tourle Thomson.[4] The second-in-command, and the most senior officer present throughout the entire expedition, was CommanderJohn Maclear. Willemoes-Suhm died and was buried at sea on the voyage toTahiti. Lords Campbell and Balfour left the ship in Valparaiso, Chile, after being promoted.[4]
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The first leg of the expedition took the ship fromPortsmouth (December 1872) south toLisbon (January 1873) and then on toGibraltar. The next stops wereMadeira and theCanary Islands (both February 1873). The period from February to July 1873 was spent crossing the Atlantic westwards from the Canary Islands to theVirgin Islands, then heading north to the North Atlantic archipelago andImperial fortresscolony ofBermuda (home base of the North America and West Indies Station), east to theAzores, back to Madeira, and then south to theCape Verde Islands. During this period, there was a detour in April and May 1873, sailing from Bermuda north toHalifax and back, crossing theGulf Stream twice with the reverse journey crossing further to the east.[12]
After leaving the Cape Verde Islands in August 1873, the expedition initially sailed south-east and then headed west to reachSt Paul's Rocks. From here, the route went south across the equator toFernando de Noronha during September 1873, and onwards that same month toBahia (now called Salvador) in Brazil. The period from September to October 1873 was spent crossing the Atlantic from Bahia to theCape of Good Hope, touching atTristan da Cunha on the way.[12]
December 1873 to February 1874 was spent sailing on a roughly south-eastern track from the Cape of Good Hope to the parallel of60 degrees south. The islands visited during this period were thePrince Edward Islands, theCrozet Islands, theKerguelen Islands andHeard Island. February 1874 was spent travelling south and then generally eastwards in the vicinity of theAntarctic Circle, with sightings of icebergs, pack ice and whales. The route then took the ship north-eastward and away from the ice regions in March 1874, with the expedition reachingMelbourne in Australia later that month. The journey eastward along the coast from Melbourne to Sydney took place in April 1874, passing byWilsons Promontory andCape Howe.[12]
When the voyage resumed in June 1874, the route went east from Sydney toWellington in New Zealand, followed by a large loop north into the Pacific calling atTonga andFiji, and then back westward toCape York in Australia by the end of August. The ship arrived in New Zealand in late June and left in early July. Before reaching Wellington (on New Zealand's North Island), brief stops were made at Port Hardy (ond'Urville Island) andQueen Charlotte Sound andChallenger passed through theCook Strait to reach Wellington.[citation needed]
The route from Wellington to Tonga went along the east coast of New Zealand's North Island, and then north and east into the open Pacific, passing by theKermadec Islands en route toTongatabu, the main island of the Tonga archipelago (then known as the Friendly Islands). The waters around the Fijian islands, a short distance to the north-west of Tonga, were surveyed during late July and early August 1874. The ship's course was then set westward, reachingRaine Island—on the outer edge of theGreat Barrier Reef—at the end of August and thence arriving at Cape York, at the tip of Australia'sCape York Peninsula.[12]
Over the following three months, from September to November 1874, the expedition visited several islands and island groups while sailing from Cape York to China andHong Kong (then aBritish colony). The first part of the route passed north and west over theArafura Sea, withNew Guinea to the north-east and the Australian mainland to the south-west. The first islands visited were theAru Islands, followed by the nearbyKai Islands. The ship then crossed theBanda Sea touching at theBanda Islands, to reach Amboina (Ambon Island) in October 1874, and then continuing toTernate Island. At the time, all these islands were part ofNetherlands East-Indies and are since 1949 part ofIndonesia.[citation needed]
From Ternate, the route went north-westward towards the Philippines, passing east of Celebes (Sulawesi) into theCelebes Sea. The expedition called at Samboangan (Zamboanga) on Mindanao, and thenIloilo on the island of Panay, before navigating within the interior of the archipelago en route to the bay and harbour ofManila on the island of Luzon. The crossing north-westward from Manila to Hong Kong took place in November 1874.[12]
After several weeks in Hong Kong, the expedition departed in early January 1875 to retrace their route south-east towards New Guinea. The first stop on this outward leg of the journey was Manila. From there, they continued on to Samboangan, but took a different route through the interior of the Philippines, this time touching at the island ofZebu. From Samboangan the ship diverged from the inward route, this time passing south of Mindanao—in early-February 1875.[citation needed]
Challenger then headed east into the open sea, before turning to the south-east and making landfall at Humboldt Bay (nowYos Sudarso Bay) on the north coast of New Guinea. By March 1875, the expedition had reached theAdmiralty Islands north-east of New Guinea. The final stage of the voyage on this side of the Pacific was a long journey across the open ocean to the north, passing mostly west of theCaroline Islands and theMariana Islands, and on 23 March 1875 discovering the Mariana Trench (see ‘Challenger Deep’ below).Challenger reached port inYokohama, Japan, in April 1875.[12]
Challenger departed Japan in mid-June 1875, heading east across the Pacific to a point due north of theSandwich Islands (Hawaiʻi), and then turning south, making landfall at the end of July atHonolulu on the Hawaiian island ofOʻahu. A couple of weeks later, in mid-August, the ship departed south-eastward, anchoring atHilo Bay offHawaiʻi Island, before continuing to the south and reachingTahiti in mid-September.[citation needed]
The expedition left Tahiti in early October, swinging to the west and south of theTubuai Islands and then heading to the south-east before turning east towards the South American coast. The route touched at theJuan Fernández Islands in mid-November 1875, withChallenger reaching the port ofValparaiso in Chile a few days later. The next stage of the journey commenced the following month, with the route taking the ship south-westward back out into the Pacific, past the Juan Fernández Islands, before turning to the south-east and back towards South America, reaching Port Otway in theGulf of Penas on 31 December 1875.[12]
Most of January 1876 was spent navigating around the southern tip of South America, surveying and touching at many of the bays and islands of the Patagonian archipelago, theStrait of Magellan, andTierra del Fuego. Locations visited here include Hale Cove, Gray Harbour, Port Grappler, Tom Bay, all in the vicinity ofWellington Island; Puerta Bueno, nearHanover Island; Isthmus Bay, near theQueen Adelaide Archipelago; and Port Churruca, nearSanta Ines Island.[citation needed]
The final stops, before heading out into the Atlantic, werePort Famine,Sandy Point and Elizabeth Island.Challenger reached theFalkland Islands towards the end of January, calling atPort Stanley and then continuing northward, reachingMontevideo in Uruguay in mid-February 1876. The ship left Montevideo at the end of February, heading first due east and then due north, arriving atAscension Island at the end of March 1876.[citation needed]
The period from early- to mid-April was spent sailing from Ascension Island to the Cape Verde Islands. From here, the route taken in late April and early May 1876 was a westward loop to the north out into the mid-Atlantic, eventually turning due east towards Europe to touch land atVigo in Spain towards the end of May. The final stage of the voyage took the ship and its crew north-eastward from Vigo, skirting theBay of Biscay to make landfall in England.[12]Challenger returned toSpithead,Hampshire, on 24 May 1876, having spent 713 days out of the intervening 1,250 at sea.[3]
TheRoyal Society stated the voyage's scientific goals were:[13][1]
One of the goals of the physical measurements for HMSChallenger was to be able to verify the hypothesis put forward by Carpenter on the link between temperature mapping and global ocean circulation in order to provide some answers on the phenomena involved in the major oceanic mixing. This study is a continuation of the preliminary exploratory missions ofHMSLightning andHMSPorcupine.[1] These results are important for Carpenter because his explanation differed from that of another renowned oceanographer at the time, the AmericanMatthew Fontaine Maury.[14] All these results of physical measurements were synthesized byJohn James Wild (i.e. the expedition's secretary-artist) in his doctoral thesis at the University of Zurich.[15]
A second important issue concerning the collection of different kinds of physical data on the ocean floor was the laying of submarine telegraph cables. Many transoceanic cables were being laid in the 1860s and 1870s and their efficient laying and operation were matters of great strategic and commercial importance.[1]
At each of the 360 stations the crew measured the bottom depth and temperature at different depths, observed weather and surface ocean conditions, and collected seafloor, water and biota samples.Challenger's crew used methods that were developed in prior small-scale expeditions to make observations. To measure depth, they would lower a line with a weight attached to it until it reached the sea floor. The line was marked in 25-fathom (150 ft; 46 m) intervals with flags denoting depth. Because of this, the depth measurements fromChallenger were, at best, accurate to the nearest 25-fathom (150 ft; 46 m) demarcation. The sinker often had a small container attached to it that would allow for the collection of bottom sediment samples.[1]
The crew used a variety of dredges andtrawls to collect biological samples. The dredges consisted of metal nets attached to a wooden plank and dragged across the sea floor. Mop heads attached to the wooden plank would sweep across the sea floor and release organisms from the ocean bottom to be caught in the nets. Trawls were large metal nets towed behind the ship to collect organisms at different depths of water.[16] Upon the retrieval of a dredge or trawl,Challenger crew would sort, rinse, and store the specimens for examination upon return. The specimens were often preserved in either brine or alcohol.[citation needed][17]Manganese nodules and sediment, which was later found to containmicrometeorites, was collected from the ocean floor.[18]
The primary thermometer used throughout theChallenger expedition was theMiller–Casella thermometer, which contained two markers within a curved mercury tube to record the maximum and minimum temperature through which the instrument traveled.[14] Several of these thermometers would be lowered at various depths for recording. However, this design assumed that the water closer to the surface of the ocean was always warmer than that below. During the voyage,Challenger's crew tested thereversing thermometer, which could measure temperature at specified depths. Afterwards, this type of thermometer was used extensively until the second half of the 20th century.[13] After the return ofChallenger, C.W. Thomson askedPeter Tait to solve a thorny and important question: to evaluate the error in the measurement of the temperature of deep waters caused by the high pressures to which the thermometers were subjected. Tait solved this question and continued his work with a more fundamental study on the compressibility of liquids leading to his famousTait equation.[19]William Dittmar of Glasgow University established the composition of seawater. Murray andAlphonse François Renard mapped oceanic sediments.
Thomson believed, as did many adherents of the then-recenttheory of evolution, that the deep sea would be home to "living fossils" longextinct in shallower waters, examples of "missing links". They believed that the conditions of constant cold temperature, darkness, and lack of currents, waves, orseismic events provided such a stable environment that evolution would slow or stop entirely.Louis Agassiz believed that in the deeps "we should expect to find representatives of earliergeological periods."Thomas Huxley stated that he expected to see "zoological antiquities which in the tranquil and little changed depths of the ocean have escaped the causes of destruction at work in the shallows and represent the predominant population of a past age." Nothing of the sort came to pass, however; though a few organisms previously regarded as extinct were found and cataloged among the many new discoveries, the harvest was typical of what might be found in exploring any equivalent extent of new territory. Furthermore, in the process of preserving specimens inalcohol, Thomson and chemist John Young Buchanan realised that he had inadvertentlydebunked Huxley's prior report ofBathybius haeckelii, anacellularprotoplasm covering the sea bottoms, which was purported to be the link between non-living matter and living cells. The net effect was a setback for the proponents of evolution.[5]
On 23 March 1875, at sample station number 225 located in the southwest Pacific Ocean between Guam and Palau, the crew recorded a sounding of 4,475 fathoms (26,850 ft; 8,184 m),[1] which was confirmed by a second sounding.[20] As shown by later expeditions using modern equipment, this area represents the southern end of theMariana Trench and is one of the deepest known places on the ocean floor.
Modern soundings to 6,012 fathoms (36,070 ft; 10,994 m) have since been found near the site ofChallenger's original sounding.[21]Challenger's discovery of this depth was a key finding of the expedition in broadening oceanographic knowledge about the ocean's depth and extent; the depression, theChallenger Deep, now bears the name of the vessel and its successor,HMSChallenger II, which in 1951 identified a depth of 5,944 fathoms nearby.[22]Thomas Gaskell, the Chief Scientist on HMSChallenger II, observed that the later measurement
was not more than 50 miles from the spot where the nineteenth-centuryChallenger found her deepest depth [...] and it may be thought fitting that a ship with the nameChallenger should put the seal on the work of that great pioneering expedition of oceanography.[23]
The expedition also verified the existence of the Mid-Atlantic Ridge extending from the southern hemisphere to the northern one.[1]
Findings from theChallenger expedition continued to be published until 1895, 19 years after the completion of its journey, by the Challenger Office, Edinburgh, established for that purpose. The report contained 50 volumes and was over 29,500 pages in length.[5] Specimens brought back byChallenger were distributed to the world's foremost experts for examination, which greatly increased the expenses and time required to finalize the report.[24] The report and specimens were displayed at theBritish Natural History Museum from January to July, 2023.[25] Some specimens, many of which were the first discovered of their kind, are still examined by scientists today.[26]
A large number of scientists worked on categorizing the material brought back from the expedition including the paleontologistGabriel Warton Lee.George Albert Boulenger, herpetologist at the Natural History Museum, named a species of lizard,Saproscincus challengeri, afterChallenger.[27]
Before theChallenger expedition, oceanography had been mainly speculative.[5] As the first true oceanographic cruise, theChallenger expedition laid the groundwork for an entire academic and research discipline.[8] "Challenger" was applied to such varied phenomena as theChallenger Society for Marine Science, the oceanographic and marine geological survey shipGlomar Challenger and theSpace ShuttleChallenger.[28]
To prepare the ship for scientific work, HMS Challenger's refit commenced at the Royal Navy's Sheerness Dockyard in June 1872. The Admiralty estimated that repairs and modifications would require six months of planning and work.
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