Letters written and data recorded from the HMS Challenger

Station recordings from HMS Challenger

Here we are again! I told you all last time I would let you see some of the original data from the reports from the HMS Challenger. Let’s look at some recordings from station 256. This was on the journey from Yokohama to the Sandwich Islands on July 21st 1875.




As you can see they measured:

  • Date and times
  • Longitude
  • Latitude
  • Air temperature
  • Water temperature at different depths
  • Density
  • What they found deposited at the bottom
  • Amount of carbonic acid in the water
  • The water current
  • Species found






They even went in to detail about an albatross having a cotton handkerchief around its neck. They certainly gave very detailed accounts of what they found. The material and species found were sent to scientists around the world once the expedition had finished, allowing them to be identified and written in the reports.


The letters and diary of Joseph Matkin


(Photograph and quotes from: Philip F Rehbock, 1992.  
At Sea with the Scientifics: The Challenger Letters of Joseph Matkin. 
University of Hawaii Press).

There were letters and diaries written by members of the crew and some of these have been documented. Joseph Matkin, only 19 when the voyage began, was a member of the crew aboard Challenger and was a ship’s steward’s assistant for the whole voyage. He wrote a journal throughout which gives a different and more personal perspective of the voyage to the scientists. He speaks of food the crew ate, the people they met on land, the weather and also deaths that occurred along the way. Here are some quotes from a book published containing his diary and letters.

February 9th, 1873 “Last night one of the men caught a shark, about 6 feet in length…he was lively as ever..The old gentleman is now being eaten for dinner in the mess of the men who caught him”
June 28th, 1874 “The deceased Edw Winton was one of the finest and steadiest seamen in the ship, was about 25 years old, & married just before we left England…no one knows whether he was stunned against the ship’s side by the sea, or he might have been struck by the fans of the screw as he drifted under the stern.”
February 24th, 1875 “The natives are undoubtedly lazy, but the Spaniards do very little but smoke, drink coffee and fan themselves, the only hard workers in the Philippine islands are the Chinese.”
July 27th, 1875 “The island of Oahu has a very pleasant rural appearance…the weather is much hotter here; Thermometer 85° in the shade, and over 120° in the sun. The ship is already full of flies,& the ravenous but playful Mosquitos are only waiting for us to turn in before commencing their onslaught.”

The writing is fascinating and his language shows that he was obviously quite a well-educated man. I recommend having a read of these letters if you are interested in a more personal view of the voyage.

Will write again soon!

Measurements and equipment on HMS Challenger

As I explained in our first post, the HMS Challenger expedition aimed to find out the chemistry and physics of the deep-sea. However, what and how did they measure?

Measurements and equipment used on HMS Challenger

DSCF3897   DSCF3896   DSCF3899   DSCF3898   DSCF3901

To measure temperature: Miller-Cassela thermometers

One of the main components they wanted to measure was surface, bottom and intermediate temperatures of the sea. For almost all the observations, the Miller-Cassela thermometer was used. This was a  minimum and maximum thermometer (in other words, it  showed the minimum and maximum temperature of the water). As a series of temperatures were measured at different depths, this type of thermometer could be relied upon..to a certain extent. More accurate thermometers were needed at deep depths but the plan to get any was unsuccessful before the end of the expedition.

To measure specific gravity: Piezometers and hydrometers














First off – what is specific gravity? In simple terms and in this case, it is the comparison of the density of sea water with the density of pure water. This all gets a little confusing but I will try to explain it simply.

Specific gravity was measured using devices called hydrometers and piezometers, measuring mass and water pressure. This can then be used to calculate density and so specific gravity.

So why was this useful for the expedition?  Firstly, water pressure was used to measure depth and you could see how the density of the seawater changes at different depths. It was also used to make sure that the temperature was recorded accurately – the thermometers gave you the minimum and maximum temperature and this would be accurate if at all areas the deeper the water the colder it gets. However, this is not always the case. For example, ice is less dense than seawater and so floats on top, despite being colder than the water below it. The crew worked out that a fall of one degree of temperature had the same effect as an increase of pressure equal to 430 fathoms. From this, temperature could be recorded correctly. How to measure and what to measure with was certainly well thought out! Now on to how they collected water – a little easier on the brain!



To collect water during the HMS Challenger expedition: Buckets and Bottles

When collecting water, water from the surface was collected simply with a bucket. Water from the bottom, however, was collected by specifically designed instruments, for example the Slip Water-Bottle. This was basically a brass cylinder that takes in water once it reaches the bottom. A similar water bottle, called the Stop-Cock Water Bottle, was used to collect water at intermediate depths.










So that is just some of the main equipment used aboard HMS Challenger to gather important data. The temperatures recorded are still being used now to compare how the ocean’s temperature has changed over time so it was well worth the effort.

That is me for now…in the next blog post I will show you examples of some of the data collected from a station, including some specimens that were found. Speak soon!