Simple environmental data measures required complicated processes in past
When my old friend, EPA scientist Don Lear, died in 1996, he extracted what amounted to a deathbed promise that I would succeed him as historian for AERS, the Atlantic Estuarine Research Society. Its members helped to establish the Coastal and Estuarine Research Federation. AERS is an affiliate society to that organization.
I've had that role for a number of years, and with the help of devoted and skilled members who donated their time, we eventually transferred the organization's archives to the Smithsonian Institution. AERS' president, Leila Hamdan of the U.S. Naval Research Laboratory, asked me to speak at the organization's 60th anniversary banquet this November. This column features highlights of that presentation.
Preparing my lecture, I thought about this organization, which in 1948 was conceived as a forum among 22 scientists to send out trial balloons and exchange ideas, always with an emphasis on students and their work. AERS was often a place where young people made their debuts on the scientific presentation stage-a role it continues to this today.
In preparing my talk, I realized how hard it had been in the past to collect environmental and natural resource data that today are matter of course. Many of the statistical analyses we use today were unheard of when I entered the stage in 1964.
I thought I would bridge the gap for this generation, for whom so many things are routine: data loggers, computers of once unimaginable capability, remote telemetering, GPS, Googling, cell phones. Even I now lecture using only Power Point digital images from my laptop as my library of 23,000 color slides slowly fades into obsolescence.
I offered my audience a peek into the generations of scientists who really started the disciplines of oceanography and biology, which has since diversified into ecology, coastal, estuarine and marine sciences; environmental sciences; and engineering and natural resources management, disciplines unheard of many decades ago, but perfectly familiar today.
In the 19th century, seamen knew that even in tepid summer surface temperatures, a bottle of wine lowered deep in the sea could be hauled up delightfully cold-as low as 49 F. They also discovered that if one lowered it too deeply, the immense pressure would implode the cork, and the bottle would come up with the cork inside and the wine exchanged for seawater. It was assumed that this terrible crushing pressure made the sea floor a chill, absolutely dark and lifeless place
In the early 1870s, a dredge hauled along the ocean floor at a depth of 1,260 fathoms (about 7,650 feet), returned to the surface with a large number of unique organisms. This launched efforts to investigate the world's oceans. The British steam / sail corvette Challenger was fitted out for such voyages. Sir Wyville Thompson, a Scottish geologist, commanded the investigation. His work and that of his scientific party was to change perception of the ocean world.
Most of Challenger's guns were removed, making room for wet-biology laboratories, thousands of preserving jars, drums of alcohol and other chemicals and then-state-of-the-art chemistry apparatus. Complex glass tubes and flasks were secured to table and bulkhead to prevent their being thrown about at sea, and Challenger's gun ports were sometimes used to vent noxious gasses from one analytical reaction or another. The ship's waist was fitted with booms and derricks to hoist big dredges and lower strings of sampling devices. Challenger's cruises took place 1872-3. Its reports came out as ponderous volumes in 1878.
I own a volume of the "Voyage of the Challenger" survey series, a voyage on the Atlantic. Thompson, with a string of credentials: knight, doctor of laws, doctor of science, fellow of the Royal Statistical Society of London and Edinburgh, fellow of the Linnean Society and fellow of the Geological Society, is the author. It contains several maps of the voyages, detailed drawings of sea-creatures no human had seen (no photographs), woodcuts of the ship on station and its scientific gear, as well as unusually costumed inhabitants of the Atlantic's ocean islands. The text includes such arcane observations as potato culture in the Bermudas.
One of Challenger's missions was to map the depths of the ocean floor. Mariners had often tied several ropes together and sounded to immense depths, but there was a point when a ship could not carry enough rope to reach bottom and would simply be described as going "off soundings."
In the days before electronic instrumentation, this was a serious roadblock in describing our world. One of the better solutions, using piano wire, was developed by U.S. Navy Capt. Charles Dwight Sigsbee. In 1875, he published a diagram of his machine, which was state of the art for deep water until electronic sounders were developed about 1923. Wire was also used on the Challenger.
Sigsbee went on to inadvertent fame as captain of the battleship USS Maine, which exploded and sank in Havana's harbor in January 1898 while on a diplomatic mission. The event unleashed a public outcry and triggered the Spanish American War. Sigsbee, who survived in his cabin, was made something of a hero. He later commanded a squadron returning the remains of John Paul Jones to the United States. They currently lie at the U.S. Naval Academy in Annapolis, MD.
Children were named after Sigsbee, and the skipjack Sigsbee, built 1901 at Deal, MD, still sails with the Living Classrooms Foundation in Baltimore. A Sigsbee Sounding Machine was used aboard the U.S. Coast Survey's USS Albatross, a square-rigged sail /steam vessel that was in the Chesapeake for a small part of its career.
All of the modern Chesapeake's monitoring data revolves around "profiles," a series of data readings including depth, which allow us to understand and analyze structure in the water column, to help plan strategies to improve conditions. Without the electronic aids we take for granted, constructing profiles was a great challenge in the 1870s. Even the chemical titration method for analyzing oxygen-the Winkler method-a vital living resource parameter, was not published until 1888. Constructing profiles generally relied on deploying strings of instruments.
Getting a water sample from a great depth relied on developing a container that would remain open and flushing during descent, then somehow be closed and remain sealed until its return to the surface. One such device was the Kemmerer bottle, named after its developer, a limnologist-one who studies deep lakes. Closing it required a shaped weight or messenger, that slid down the suspending wire and struck a release latch atop the bottle, closing both ends with rubber stoppers. If the messenger failed to trip the latch, there was no sample collected. These early devices-made of brass or bronze-would, be unacceptable today because of our understanding of the need to measure trace metals that are so active biologically.
Today, there are a number of such devices and some, in nonreactive PVC plastic are closed by elastic tubing and silicone "toilet plungers." Once a sample returns to the surface, it can be used for chemical analysis. Specific gravity (analogous to salinity, which was not part of the lexicon in those days) was determined using a hydrometer. Today, salinity is a broad determiner of what organisms can live in a particular habitat, as well as the sea. It can also be used to trace water masses as they are moved about by currents and winds.
Salinity, itself, is a complex concept, but what chemists sought was a precise measure of some property that approximated total dissolved solids. Salt was dominant in the sea, making it a good place to start.
When Capt. James Cook made his voyages throughout the Pacific (1766-79), among the many things brought back to Europe were bottles of water from various sites that eventually resided in the laboratory at Charlottenlund, Denmark. When the international community agreed that scientist Martin Knudsen should develop a standard method for measuring salinity these were among the wide selection of water samples analyzed.
Chlorinity-a component of salt NaCl-was measured. On the open sea, chlorinity could be related by an equation to total dissolved solids or salinity, expressed in "parts per thousand" or 0/00). Knudsen's method, titrating with silver nitrate, was widely adopted between 1900 and 1903.
Imagine the work necessary to develop a profile of salinity in a water column tens of thousands of feet deep.
And what about temperature? One could lower a thermometer to great depths, but it would take hours to bring it back to the surface, during which time it would equilibrate to external water temperature. Some unspecified registering thermometers aboard the Challenger were lowered to the bottom where at one station, two were crushed by the extreme pressure at 3,875 fathoms (23,250 feet).
One such thermometer, widely used into the 20th century, was the "reversing thermometer" a treasure of the glass-blower's art, which was usually lowered encased in a protective nickel-plated brass housing. These were sent down on the wire in a upright position, and when tripped by the messenger, they would flip by gravity 180 degrees. The snapping motion would separate the mercury column, leaving it "registered" on the water temperature at depth. A string of these would give a profile, but each had unique expansion coefficients because of variations in glass blowing that had to be applied to the temperature indicated. At depth, the mercury and glass had also been massively squeezed by thousands of pounds of water pressure, requiring another correction for each depth.
On deck, the entire device was warmed or cooled to shipboard temperature requiring yet another correction. Once these were all applied, and a lens used to read the indicated temperature, it could be accurate within a few hundredths of a degree. Try that over a water column of 3,000 fathoms.
A single reversing thermometer in recent times (circa 2003) would have cost $1,200 delivered, more than $300 of which was the elaborate Homeland Security requirement for shipping mercury, a hazardous material. The manufacturer, Khalsico, went out of business, and with it, the oceanographic glassblower's art of making these elegant, precise masterpieces.
Mechanics-and many oceanographers were excellent ones-sought ways to get these profiles, at least approximate ones, as a continuous data set. The result was a bathythermograph or "BT." This looked something like a small shoulder-launched rocket. I would not want to be carrying one around any large airport or military establishment today. The rocket was simply a gravity-friendly shape that would streamline the instrument's trip down. Inside was a bellows arrangement that would compress a spring proportional to depth, and a bimetallic thermometer element, like the dial oven thermometers in homes. Both were connected to little metal styluses that moved two dimensionally in response to depth and temperature. They scratched a line in a layer of soot deposited on a mounted microscope slide, making the data record.
Once the slide was recovered, someone had to sit at a low-power magnifier and enter all of the temperature and depth coordinates into lab notebooks.
I don't know what instrument Thompson's men used to record temperature at depth aboard the Challenger, but he described the record as extremely delicate; and that even a small jerk during recovery could move the pointer and make the numbers uncertain.
By the mid 20th century, rudimentary electronic devices, although cumbersome, were becoming widely available to coastal and marine scientists. Depth, salinity and temperature became the core set of oceanographic data, and were vital to winning the sea components of World War II's maritime and submarine battles.
These parameters were used by one of AERS' founding members, Donald W. Pritchard, when he began his investigations in Chesapeake Bay after World War II. His investigations refined what was known about the circulation of tides and currents in the Chesapeake and formed the first real definition of an estuary. His research cruises on the Bay are also the foundation of an environmental monitoring network still in place today.
Electronic data sensing, packaging, transmitting, recording and analysis today are all light years ahead of the Challenger. Modern instruments can gather all of these, for long periods, with a unit hardly bigger than the old, reversing thermometer.
Pritchard's granddaughter, Alicia Pritchard, an undergraduate student at St. Mary's College in Maryland, gave her first scientific paper at the AERS 60th anniversary meeting this November, in conjunction with Chuck Gallegos of the Smithsonian Institution's Environmental Research Center, Edgewater, MD. She studied the oyster Crassostrea virginica, the quintessential species of Chesapeake Bay. Pritchard, who died in 1999 (See "Past is Prologue," June 1999.) would have been proud of her beyond words.
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