HMS Challenger's Daring Expedition

The small engine wines as it methodically hoists the heavy load out of the deep blue waters, the weighted woven bag dangles from its heavy wood support as it’s lifted up and seawater drips out of it. The pulley creaks as the bag swings in from the side and is lowered onto the deck. You and several men take a moment to make sure there are no holes or major damage before peering inside at the thick gray ooze, eager to discover what it holds. 

Sketch of an octopus by John James Wild. Courtesy of lazerhorse.

Overview

Science saw a veritable renaissance during the Victorian Era as the middle and upper classes became obsessed with learning about the world around them. Breakthroughs in technology allowed for new discoveries that excited many and made governments all the more eager to claim advancements in their name. Natural History was of particular interest as many wanted to know how the Earth was created, and after Darwin’s expedition and evolutionary theory, wanted to know if/how animals and humans evolved. This set the stage for a naturalist named Wyville Thomson to propose a daring scientific expedition, a roughly five year trip where him and other scientists would circumnavigate the globe in order to study the makeup of the deep sea. 

Charles Darwin, the man who really helped spurn the scientific revolution in Victorian England. Courtesy of Richard Milner.

In 1870 Thomson brought his idea to the attention of the Royal Society of London who expressed much interest in it and helped him set the main goals for the expedition. First was to find out what the physical conditions of the deep sea were like in regards to temperature, gravity, water circulation and other variables. Second, discover what sea water consisted of at various depths including chemical makeup. Third, to find out what the deposits on the ocean floor are made of and where these deposits originated. Fourth, to discover what sorts of flora and fauna lived at different depths and what, if any, lived on the ocean floor. This last one was of particular importance to Thomson as a new idea called the “azoic” theory (“a” meaning without and “zoic” meaning life) was being accepted as fact. This theory stated that no life could live below 300 fathoms (1,800 feet) as the pressure was too intense for any creature to withstand. Thomson was almost certain this theory was incorrect as sailors and fisherman had reportedly caught fish at depths greater than this.  

With the goals set and excitement for the idea growing, the Royal Society of London requested that the British Government lend them a ship that could be used for the voyage. The Royal Navy obliged and with ship and funding in place Thomson set about gathering a crew and supplies for the expedition that was set to sail in late 1872. 

Edward Forbes, the originator of the azoic theory. Public Domain.

The Men 

The leaders of the expedition would be Scottish naturalist Charles Wyville Thomson and Scottish-Canadian naturalist John Murray. Being 42 at the start of the expedition, Thomson had already built a very respectable career as a professor in Natural History, teaching at the prestigious Edinburgh University where his primary focus was marine invertebrates. However much of his notoriety within the scientific community was gained because he had participated in two previous deep sea dredging expeditions in the seas north of Scotland. Thomson was particularly interested in the life that existed at the bottom of the ocean and was constantly studying what specimens he could find, and during the expedition he would work tirelessly to discover the secrets of the watery depths. 

Wyville Thomson. Courtesy of the BBC Hulton Picture Library.

John Murray, the other leader of the expedition, was a Canadian who has been described as outspoken and high spirited. Being 31 at the start of the expedition, he also studied at Edinburgh University though he rarely attended lectures and never took exams. He was more of an independent thinker and much preferred to study on his own, luckily for him the school still saw his merit and was flexible enough to accommodate his free spirit. He had an almost unparalleled love for natural history and was good at seeing the big picture and how all pieces fit together. As such he would end up being the lead author describing their findings after the voyage was over.

John Murray. Courtesy of Britannica.

Henry Nottidge Mosely was in his late 20s at the start of the expedition. He had developed a great interest in Natural History early on in his life that stuck with him, not doing his best in school because he much preferred spending time doing experiments in his homemade laboratory. He enrolled in Exeter College, Oxford where he planned on taking a degree in either mathematics or the classics, but found that both made him extremely unhappy and ended up spending much of his time milling about Oxford collecting specimens for his personal collection. One of his father’s friends had a talk with him one day and quickly realized that Mosely was wasting his time there, promptly he introduced the budding naturalist to the professor of anatomy. Mosely enrolled in the newly established Honor School of Natural Science at Oxford and quickly became one of its top students. He graduated with a first-class degree in natural sciences and a few years later was selected for the expedition. He was ecstatic and spent months creating a state-of-the-art zoological laboratory aboard the ship. Oddly enough he would admit that his excitement was more due to his thirst for adventure than his interest in natural history. 

Artist portrait of Henry Nottidge Mosely. Courtesy of Oxford University Archives.

John Buchanan was 29 at the start of the expedition and had come to the field of science a bit late. Originally he had gone to university to obtain a degree in the arts but quickly discovered a fascination with chemistry. He switched his degree over and was described as being a very practical thinker, something that is likely more important in chemistry than any other scientific field. He was able to make his own instruments and was even a quite capable glass blower, skills that would be immensely useful on a ship going to remote places and braving some of the roughest seas in the world. Once selected he spent time setting up a small chemistry lab in one of the ship's gun bays and tried to make it as versatile as possible. 

John Buchanan. Courtesy of the Royal Society of Chemistry.

German zoologist Rudolf von Willemoes Suhm was the youngest of the scientists at only 25 and had actually only been selected for the expedition by chance. Originally he had planned to be a lawyer but had spent so much time studying Natural Science during his first year of university that he changed his degree to zoology. Only two and a half years after this he took a doctors degree and gained an interest in marine invertebrates. In October of 1872, not but two months before the expedition was set to start, the German survey ship Phoenix stopped at Edinburgh port for coal and it is here that Suhm and Thomson met. The two men hit it off immediately and Thomson invited him to be part of the expedition on the spot, Suhm was overjoyed and eagerly accepted. 

Artists drawing of Rudolf von Willemoes Suhm. Courtesy of All Posters.

John James Wild was Wyville Thomson’s secretary and the official artist of the voyage. He made countless sketches and detailed drawings of the scientist's findings, oftentimes doing his drawings directly beside Thomson as he performed his experiments. 

John James Wild. Public Domain.

The captain of their ship was the venerable George Nares who was one of the best surveyors in the Navy and would later go on to win fame as an Arctic explorer. Under his command were an additional 23 naval officers and a crew of 217 bluejackets (sailors), marines, and engineers. Everyone necessary to ensure the trip went as smoothly as possible. 

Captain George Nares. Courtesy of Wellcome Images.

The Ship 

The vessel allocated for the scientific journey was the HMS Challenger. The wood hulled ship was built at the Royal Navy Shipyards at Woolwich and launched on February 13, 1858. She was a British Navy corvette, the smallest class of warship, measuring 200 feet long and had a displacement of 2,300 tons. For power she had three square masts and an auxiliary coal fired engine that provided 1,234 horsepower to two twin bladed propellers, most of the time the ship would rely on its sails and only use the engine when needed or when dredging samples from the ocean floor. Once handed over to the scientists it was converted into an oceanographic vessel, 15 of her 17 guns along with their ammunition were removed to make space for laboratories and science stations. The Challenger became the first ship ever to be completely dedicated to scientific discovery. 

The HMS Challenger. Courtesy of Fine Art America.

The upper or top deck was full of rigging for the masts, rope for sounding and dredging, pulleys, and small boats used to go to shore. It also had a small donkey engine that would be used to hoist the ropes and sounding wire. Below this was the main deck which housed a large cooking range that took up much of the middle part of the ship, and around it were the quarters for the senior officers and the scientific team. At the aft (rear) of the main deck was the naturalists main laboratory where specimens could be studied, catalogued, and preserved, much of J. J. Wild’s sketches were also done here. It was dimly lit with only three skylights providing light during the day and oil lamps being used at night. Below this was the lower deck where the junior officers, blue jackets, and marines stayed. This level was even darker and less ventilated than the previous one and the men slept in shared rooms suspended in hammocks. Below this was the hold where coal, food, and additional supplies and gear were stored, as well as the engine and boiler rooms. 

The main laboratory aboard the Challenger. Courtesy of Discover Magazine.

The Equipment 

In order for the scientists to properly do research they had a wide range of instruments that could take temperature, measure ocean depth, collect samples, and other data. In order to gauge the depth of the ocean they used a technique known as sounding. This involved a rope or wire being fed overboard with a round weight on the end that would keep the line taut and help it sink. The weighted ball would also let the user know when it had reached bottom and allowed for them to find the depth of that spot. Additionally the ball had a device on the end that would collect a small sample that gave them something to study as well as acting as a way to confirm that they had in fact hit the bottom. 

Different devices used on the expedition. From left to right; bottom water sampler, sounding weight, the first wireframed dredge, mercury thermometer, and sounding lines. Courtesy of Woods Hole Oceanographic Institute.

For temperature they most frequently used the Miller-Casella maximum and minimum mercury thermometers. This was a U-shaped thermometer filled with mercury that could provide the men with the maximum and minimum temperatures experienced during its dive. Bulbs of creosote would push the mercury during a change in temperature which in turn pushed one of the two spring loaded metal indexes that stayed in place at the maximum and minimum ranges. In a separate bubble surrounding the mercury and creosote was one filled with alcohol that supposedly helped negate the effects pressure might have on the mercury and give a false reading. There was some trial and error at first as the thermometers would break under the immense deep sea pressure, this was soon remedied by encasing the instrument in a heavy iron box. Since they could not tell exactly at what depths the maximum and minimum temperatures were measured at they had a practice where, after the initial sounding, they would send the rope down again with thermometers spaced at intervals of every one hundred fathoms so they could tell what depth represented what temperature. The scientists also had resistance thermometers and pressure thermometers at their disposal that were more accurate, but these were not used often as they were relatively new technology and no one had any real experience using them. 

A close up sketch of the mercury thermometers. Courtesy of HMS Challenger Project.

In order to obtain samples from the ocean floor they dredged. Their original apparatus for this operation was a wireframe with a finely woven mesh bag attached to it. It took over 3 hours for the bag to sink and then the ship would have to drag it under steam power to scoop up a sample from the ocean floor. The mesh bag however did not provide satisfying results because it could not pick up larger specimens, so they switched to a different device known as a beam trawler. This used a heavy length of wood, similar to a railroad tie, that had a lead weighted net attached to either end. This net was much more flexible and brought exceedingly better results. 

Example of a beam trawler used for dredging. Public Domain.

The scientists also collected water samples from different depths by using specially made flasks. There were two types, one for bottom water samples and another for taking samples at varying depths. The bottom sampler was a slender tube with brass disks at either end and an open “mouth” on the side. When the device hit the bottom a sleeve above the upper disk disengaged and closed the mouth trapping a sample of bottom water inside. The other type of sampler was similar in that it was also a conical tube with brass disks at both ends. Water could freely flow through the disks as it descended but once the rope was pulled up the stopcocks would close and trap a sample within. 

Sketch of the water sampler used for varying depths. Courtesy of HMS Challenger Project.

The Voyage 

HMS Challenger and most of her men left Sheerness, England on October 7, 1872 in the wake of a tragedy. On November 18 a young Marine named Tom Tubbs was going up the ship's gangway in the dark when he slipped and fell into the frigid murky waters of the dock. All night shipmates and police dredged the area but it was not until early the next morning when a diver arrived that the man’s lifeless body was found. Many aboard the ship took it as an ill omen that the voyage was doomed which caused low morale. Bad weather made it even worse as they had to put into harbor twice before finally arriving at Portsmouth, England on December 12, taking five days to travel just 105 miles. They collected the rest of the scientists and took in additional stores to the point that one of the men aboard the ship, William Spry, wrote that the holds seemed, “scientifically constructed of some elastic material so as to stretch to any size.” On December 21, 1872 they left Portsmouth and officially started their voyage. 

Map showing the route traveled by the Challenger with dates. Courtesy of NOAA.

They celebrated Christmas Day aboard the ship but it was an abysmal affair. A terrible storm boasting huge swells and causing a turbulent sea made the men have to constantly hold onto their plates and utensils as they ate. Many were tossed about by the waves and those with weaker stomachs had to stay in their cabins because of sea sickness. The officers were particularly angered as their roast turkey was stolen, and as the rest of the crew realized a thief was on board morale sank even lower. 

Shortly after leaving England they stopped in Lisbon, Portugal which helped to raise the mens spirits. After leaving Lisbon they already began making discoveries when they dredged a sea lily, an organism similar to a starfish, from waters 1,000 fathoms (6,000 feet) deep. At the time the men believed it was a piece of evidence that helped prove Darwin's theories as it showed that organisms only found in fossils on land still existed at the bottom of the ocean, like Darwin had predicted. This would later be proved wrong but at the time it was a significant discovery and did also go towards proving the azoic theory wrong.

Artists depiction of the men emptying the mesh bag used for dredging. Public Domain.

Continuing their voyage from home waters to the South Atlantic they fell into a consistent routine, every 120 miles they would stop and take sounding measurements and would dredge every 300 miles. This left the scientists very happy as they had plenty of work to do but the sailors, who were used to traveling from one place to another as expediently as possible, found the stop and go utterly dull and tiresome. As they made their way across the Atlantic they kept pulling up a substance called globigerina mud. These were small nodules encrusted in manganese and phosphate secretions that collect on the bottom of the ocean, they had discovered one of the components that made up the ocean floor. Continuing across the Atlantic they also confirmed the existence of the Dolphin Rise, a rise in the ocean floor towards the middle of the Atlantic. Today we call it the Mid-Atlantic Ridge, a chain of undersea mountains that would end up leading to the discovery of how Earth's crust is formed and how tectonic plates move. 

Map showing the rise in the middle of the Atlantic known as the Mid-Atlantic Ridge. Courtesy of EurekAlert!

Not long after this they discovered what else the ocean floor was made of, red clay and fine white silica. They ran numerous experiments, John Buchanan in particular performing many chemistry tests on it, and two theories on how it formed quickly arose. The first one, which Wyville Thomson was the biggest proponent of, was that the silica originated on the ocean floor by some sort of natural phenomenon. The second, which was promoted by Buchanan, was that the silica originated more towards the surface and was made from decayed biomass. It would not be until later in their voyage when they would discover who was right. 

They reached North America but not without incident, two men had died on the way there. The first was a sailor named William Stokes who was helping haul the dredging net aboard when one of the ropes snapped and thrust an iron block into Stokes. It severely damaged his head, broke his spine and broke one of his thighs, he died of his injuries a couple hours later. The second death happened just ten days later. Adam Ebbels was a schoolmaster who was there to teach Captain Nares’s son during the voyage; he was found ghost white dead in his hammock. The ship’s surgeon performed an autopsy and found that he had died of apoplexy, what is today called a stroke. The men tried to put the deaths behind them and explored the different islands around the Carribean while also resupplying. 

The upper deck of the Challenger, visible are the dredge, pulley’s and small donkey engine. Public Domain.

As they left to go further South they found the Gulf Stream. The Gulf Stream had been discovered over 200 years earlier, but the Challenger’s team were able to find the exact depth it started and ended and how wide the stream is. As they made their way down to Brazil they made another discovery, bioluminescence. They did not fully understand at the time how it worked but many of the men were enamored by it and made the microscopic organisms much more well known to the scientific community, laying the groundwork for more study later on. 

Sketch of some sort of mollusk by John James Wild. Courtesy of Wikimedia Commons.

They sailed back across the Atlantic and around the Cape of Good Hope at the Southernmost tip of Africa. Here they refitted for the Antarctic, taking on more blankets, heavy coats, boots, and as much coal as they could carry. As they made their way past Africa and into the Antarctic they entered the Agulhas Current. This is more or less the South Atlantic equivalent of the Gulf stream and again the men took measurements and readings to find at what depth it started and ended and how wide it was. Though this may seem mundane to someone in the modern day it was extremely important and exciting information at the time, leading to groundbreaking discoveries and theories that are still being tested. 

As the scientists measured the Agulhas Current they finally came to a conclusion of what the fine white particles at the bottom of the ocean were, the leftovers of decayed biomass such as fish. Thomson had to admit that he was wrong and it was a particularly hard thing for him to do, nevertheless he persisted as they continued on into the Antarctic Circle. The ship was flanked all around by pack ice and glaciers and the men attempted to count how many they saw but abandoned the idea as there were just too many within sight at any given time. They attempted to spot and reach land but the ice filled waters were too treacherous. Most aboard the ship were miserable due to the numbing cold with frequent heavy squalls and no real way to produce heat. After attempting to do what research they could they headed North for Australia, much to the relief of the crew. 

A sketch that a man named Benjamin Shephard made while they were in the Antarctic. Courtesy of Donald Heald Rare Books.

In the South Indian Ocean they spent a great deal of time hopping from remote island to remote island collecting specimens until they reached Australia right around the beginning of 1874. The scientists did many inland expeditions collecting samples and many of the men loved the relatively new found colony, several deserted at this stop. They then travelled to New Zealand, during which tragedy struck again. A young seaman named Edward Winton was sounding when lunch was called and all but absolutely essential crew went below deck to eat. While the majority of the crew were below the sounding line wrapped itself around the anchor, Winton climbed up the anchor chain and attempted to free the line. Just then a large wave slammed into the side of the ship and Winton was knocked into the ocean, the young seamen had no chance as he was weighed down by his heavy coat and boots. It took ten minutes for anyone to realize he was gone and when they did they frantically searched the area, but tragically his body was never recovered. 

Solemnly they reached New Zealand where more inland expeditions were performed. They then island hopped until they reached Hong Kong where Captain Nares received word that he was to depart immediately to take command of an expedition to the Arctic. Many were saddened at their loss of such a great captain and some were worried about his replacement, Frank Thomas. As a sailor by the name Joe Matkin wrote, “He bears a bad name for tyranny on this station.” Luckily their doubts were assuaged as Captain Thomas appeared to be just as able as Nares was. 

One of the sketches made by John James Wild.

While traveling from Hong Kong to Japan the winds were not cooperating and the going was slow, tempers flared and some of the officers began to worry that men would start to fight. Luckily they made a major discovery that lifted everyone’s spirit, on March 23, 1875 they discovered the deepest known point in the ocean. At 4,475 fathoms (27,000 feet) the deep sea abyss that we now know as the Marianas Trench was found, later expeditions would reveal that it is actually over 37,000 feet deep. Everyone on board was jubilant and they named it Swire Deep to honor the popular young sub-lieutenant that everyone was fond of, however once they returned to Britain it was renamed to Challenger Deep. The excitement unfortunately did not last long and tempers were again running short, but reached Japan before anything bad happened. The men thoroughly enjoyed the island nation, the scientifics for the chance to study a very different culture and the sailors because of the variety of foods, alcohols, and “delicate women.” After this they made for Hawaii which they were not all that impressed with, and aside from the volcanoes they studied were actually a bit disappointed with. To add to this disappointment, not long after leaving Hawaii, another death occurred. This time it was one of the scientists. Von Willemoes Suhm, the man whom Thomson and Moseley were so fond of, died suddenly of a bacterial infection of the skin known as erysipelas. Both men were utterly devastated. He was given a burial at sea 300 miles from the coast of Tahiti. 

They sailed around Cape Horn at the tip of South America and traversed the Atlantic one more time before returning to England. Of course it could not go that simply and tragedy struck once again. While at Port Stanley in the Falkland Islands many of the men drank heavily to quell their excitement for their return home. A sailor named Thomas Bush came back to the ship heavily inebriated and fell overboard. Lieutenant Carpented dove in after him and was able to pull him out and bring him back to the ship, unfortunately the man swallowed a lot of water and ship surgeons spent an hour trying to resuscitate him before giving up. The death hit the crew particularly hard as he was a well liked man and was set to be married upon his return to England. 

Sketch made by John James Wild.

When they arrived back in England they were greeted as heroes and everyone was eager to hear about their adventure. Almost immediately the scientists began writing up their reports and continuing their research. Many likely would have used the voyage as a way to acquire fame and wealth, but the scientists of the Challenger Expedition mostly just wanted to gain knowledge. 

By the end of their voyage they had covered over 68,000 nautical miles and gathered scientific data at 362 seperate locations. Only 144 of the original 240 crew members remained, 7 had died, 5 left with Captain Nares, 26 had to be hospitalized at some point during the journey, and the rest had deserted at one of their stops. 

Sketch of a deep sea fish by John James Wild. Courtesy of the Biodiversity Heritage Library.

Afterward 

The expedition advanced scientific understanding farther than any other scientific breakthrough had in over one hundred years. It created the modern science of oceanography and helped spurn even more expeditions of the deep sea. Information gleaned from it helped create the first charts that showed water temperatures at specific depths and helped to have a better understanding of the thermocline. It disproved some major theories while providing strong evidence for others that are still studied today. All of the crew's findings were compiled in a 50 volume set that consisted of over 29,500 pages and took 23 years to complete. The data was studied by over 100 scientists after the return, and those who participated in the data collection and publishing were awarded a special Challenger Medal. 

Most of the scientists became quite famous and successful upon their return, Thomson and Murray both being knighted, and led long lives in the pursuit of science. 

The scientists and officers who took part in the expedition. Courtesy of Letters from Gondwana.

Personal Thought 

The Victorian Era is my favorite historical era and I love learning about expeditions and great feats like this. It is tragic how many died during the voyage but luckily their deaths weren’t in vain as information gleaned from the expedition is still influencing science today. Deep sea exploration is something I like as well and I was just really interested in this whole story, it’s amazing how much they discovered and found out. I mean 50 volumes is just crazy. I have the utmost respect for the men that made this journey. 

Sources 

Cover photo is courtesy of Woods Hole Oceanographic Institute

Book, The Silent Landscape: The Scientific Voyage of HMS Challenger by Richard Corfield

https://divediscover.whoi.edu/history-of-oceanography/the-challenger-expedition/

https://oceanexplorer.noaa.gov/explorations/03mountains/background/challenger/challenger.html

https://life.bio.sunysb.edu/marinebio/challenger.html

https://www.challenger-society.org.uk/History_of_the_Challenger_Expedition

https://www.geolsoc.org.uk/Plate-Tectonics/Chap3-Plate-Margins/Divergent/Mid-Atlantic-Ridge

https://www.history.noaa.gov/stories_tales/poletobeam.html

https://www.britannica.com/biography/C-Wyville-Thomson

https://www.britannica.com/biography/John-Murray