Question: Before instrumental measurements were used, how did scientists measure sea levels?
About the article "Climate change", section "Sea level change".

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Global sea level change for much of the last century has generally been estimated using tide gauge measurements collated over long periods of time to give a long-term average.
More recently, altimeter measurements — in combination with accurately determined satellite orbits — have provided an improved measurement of global sea level change.
To measure sea levels prior to instrumental measurements, scientists have dated coral reefs that grow near the surface of the ocean, coastal sediments, marine terraces, ooids in limestones, and nearshore archaeological remains.
The predominant dating methods used are uranium series and radiocarbon, with cosmogenic radionuclides being sometimes used to date terraces that have experienced relative sea level fall.
In the early Pliocene, global temperatures were 1–2˚C warmer than the present temperature, yet sea level was 15–25 meters higher than today.
The ocean surface has highs and lows, similar to the hills and valleys of Earth's land surface depicted on a topographic map.
These variations, called "ocean surface topography" or "dynamic sea surface topography" are mapped using measurements of sea surface height relative to Earth's geoid.
Earth's geoid is a calculated surface of equal gravitational potential energy and represents the shape the sea surface would be if the ocean were not in motion.
The height variations of ocean surface topography can be as much as two meters and are influenced by ocean circulation, ocean temperature, and salinity.
Ocean surface topography is used to map ocean currents, which move around the ocean's "hills" and "valleys" in predictable ways.
A clockwise sense of rotation is found around "hills" in the northern hemisphere and "valleys" in the southern hemisphere.
This is because of the Coriolis effect.
Conversely, a counterclockwise sense of rotation is found around "valleys" in the northern hemisphere and "hills" in the southern hemisphere.
Ocean surface topography is also used to understand how the ocean moves heat around the globe, a critical component of Earth's climate, and for monitoring changes in global sea level.
Ocean surface topography can be derived from ship-going measurements of temperature and salinity at depth.
However, since 1992, a series of satellite altimetry missions, beginning with TOPEX/Poseidon and continued with Jason-1 and the Ocean Surface Topography Mission on the Jason-2 satellite have measured sea surface height directly.
By combining these measurements with gravity measurements from NASA's Grace mission, scientists can determine sea surface topography to within a few centimeters.
A new satellite mission called the Surface Water Ocean Topography Mission has been proposed to make the first global survey of the topography of all of Earth's surface water--the ocean, lakes and rivers.
This study is aimed to provide a comprehensive view of Earth’s freshwater bodies from space and more much detailed measurements of the ocean surface than ever before. 
Langley invented the bolometer, an instrument for measuring infrared radiation.
The bolometer has enabled scientists to detect a change of temperature of less than 1/100,000 of a degree Celsius.
It laid the foundation for the measurements of the amount of solar energy on the Earth.
His 1881 paper, The Bolometer and Radiant Energy, became a scientific classic.
He made one of the first attempts to measure the surface temperature of the Moon, and his measurement of interference of the infrared radiation by carbon dioxide in Earth's atmosphere was used by Svante Arrhenius in 1896 to make the first calculation of how climate would change from a future doubling of carbon dioxide levels. 
Neuropharmacology did not appear in the scientific field until, in the early part of the 20th century, scientists were able to figureout a basic understanding of the nervous system and how nerves communicate between one another.
Before this discovery, there were drugs, however, that had been found that demonstrated some type of influence on the nervous system.
In the 1930s, French scientists began working with a compound called phenothiazine in the hope of synthesizing a drug that would be able to combat malaria.
Though this drug showed very little hope in the use against malaria-infected individuals, it was found to have sedative effects along with what appeared to be beneficial effects toward patients with Parkinson’s disease.
This black box method, wherein an investigator would administer a drug and examine the response without knowing how to relate drug action to patient response, was the main approach to this field, until, in the late 1940s and early 1950s, scientists were able to identify specific neurotransmitters, such as norepinephrine (involved in the constriction of blood vessels and the increase in heart rate and blood pressure), dopamine (the chemical whose shortage is involved in Parkinson’s disease), and serotonin (soon to be recognized as deeply connected to depression).
In the 1950s, scientists also became better able to measure levels of specific neurochemicals in the body and thus correlate these levels with behavior.
The invention of the voltage clamp in 1949 allowed for the study of ion channels and the nerve action potential.
These two major historical events in neuropharmacology allowed scientists not only to study how information is transferred from one neuron to another but also to study how a neuron processes this information within itself. 
Complementary and Alternative Cancer Therapy.
Pre-clinical studies indicated that MCP helped reduce the spread of prostate, colon, breast, liver, and skin cancer.
Scientists believe that MCP works by inhibiting two key processes involved in cancer progression: angiogenesis and metastasis.
Animals with these types of cancer that were fed MCP had a much lower risk of the tumor spreading to the lungs.
For example, one study examined the effects of MCP on lung metastasis from melanoma cells.
Researchers injected mice with melanoma cells.
In the mice that were also given MCP, significantly fewer tumors spread to the lungs than in the mice that did not receive the supplement.
When lung tumors did develop in the mice treated with MCP, the tumors tended to be smaller than those that formed in untreated animals.
Although animal and cell studies are quite encouraging, limited information is available about whether MCP is effective in humans.
In one of the published clinical trials, 10 men with prostate cancer were treated with MCP after standard treatment failed.
In 7 of these men, blood tests found prostate-specific antigen (PSA, a marker of prostate cancer growth).
Their PSA doubling time (a measure of how fast PSA goes up) improved in comparison with measurements done before taking MCP, indicating that MCP may have a slowing effect on the cancer's growth.
This pilot study lacked a control group or survival data, and more randomized controlled trials looking at larger groups of people should be done.".
However, taken with the information gained from animal studies, it suggests that MCP may have a role in reducing the growth and spread of cancer, and has great potential because secondary metastatic cancers are often more threatening to patients than the original tumor.
MCP seems to have positive impacts especially regarding clinical benefit and life quality for patients with far advanced solid tumors.
Modified citrus pectin should be used with, not in place of, standard cancer therapy.