First Dinosaur Fossil

“The first proof that giant dinosaurs once walked the earth.”

  • Who Discovered it?: William Buckland and Gideon Mantell.
  • Year of Discovery: 1824

How was it Discovered?


People had always found fossil bones, but none had correctly identified them as extinct species. In 1677 English man Robert Plot found what 220 years later was identified as the end of the thigh bone of a giant biped carnivorous dinosaur. Plot gained great fame when he claimed it was the fossilized testicles of a giant and said it proved that story giants were real.

Science was clearly still in the dark ages until two English men, working independently, both wrote articles on their discovery of dinosaurs in 1824. They share the credit for discovering dinosaurs.

In 1809 (50 years before Darwin’s discovery of evolution) English country doctor Gideon Mantell lived in Lewes in the Sussex district of England. While visiting a patient one day, Mantell’s wife, Mary Ann, took a short stroll and then presented him with several puzzling teeth she had found. These massive teeth were obviously from an herbivore but were far too large for any known animal. Mantell, an amateur geologist, had been collecting fossil relics of ancient land animals for several years but could not identify these teeth. He returned to the site and correctly identified the rock strata as from the Mesozoic era. Thus, the teeth had to be many millions of years old.


These teeth were not the first large bones Mantell had found, but they were the most puzzling. Mantell took them to famed French naturalist, Charles Cuvier, who thought they came from an ordinary rhinoceros-like animal. Mantell set the teeth aside.

In 1822 Mantell came across the teeth of an iguana and realized that these teeth were exact miniatures of the ones he had found 13 years earlier. Combined with other large bones he had recovered from the site, Mantell claimed that he had discovered an ancient, giant reptile that he named Iguanodon (“Iguana-toothed”). He eagerly published his discovery in 1824.

During this same period William Buck-land, a professor at Oxford University, had been collecting fossils in the Stonesfield region of England. During an 1822 outing, he discovered the jaw and several thigh bones of an ancient and giant creature. (It turned out to be the same species discovered—but not identified—by Robert Plot 150 years before.)

Buckland determined from these bones that this monster had been a biped (two-legged) carnivore. From the bone structure, Buckland claimed that it belonged to the reptile family. Thus he named it megalosaurus (giant lizard) and published a paper on it in 1824. With these two publications, the era of dinosaurs had been discovered.


Fun Facts: The word dinosaur comes from the Greek words meaning terrible lizard.” Lots of dinosaurs were named after Greek words that suited their personality or appearance. Velociraptor means “speedy robber” and Triceratops means “three-horned head.

Radio Waves

All electric and magnetic energy waves are part of the one electromagnetic spectrum and follow simple mathematical rules.

  • Who Discovered it?: James Clerk Maxwell
  • Year of Discovery: 1864

How was it Discovered?


James Clerk was born in 1831 in Edinburgh, Scotland. The family later added the name, Maxwell. James sailed easily through his university schooling to earn top honors and a degree in mathematics. He held various professorships in math and physics thereafter.

As a mathematician, Maxwell explored the world—and the universe—through mathematics equations. He chose the rings of Saturn as the subject of his first major study. Maxwell used mathematics to prove that these rings couldn’t be solid disks, nor could they consist of gas. His equations showed that they must consist of countless small, solid particles. A century later, astronomers proved him to be correct.

Maxwell turned his attention to gasses and studied the mathematical relationships that governed the motion of rapidly moving gas particles. His results in this study completely revised science’s approach to studying the relationship between heat (temperature) and gas motion.

In 1860 he turned his attention to early electrical work by Michael Faraday. Faraday invented the electric motor by discovering that a spinning metal disk in a magnetic field created an electric current and that a changing electric current also changed a magnetic field and could create physical motion.

Maxwell decided to mathematically explore the relationship between electricity and magnetism and the “electrical and magnetic lines of force” that Faraday had discovered.

As Maxwell searched for mathematical relationships between various aspects of electricity and magnetism, he devised experiments to test and confirm each of his results. By 1864 he had derived four simple equations that described the behavior of electrical and magnetic fields and their interrelated nature. Oscillating (changing) electrical fields (ones whose electrical current rapidly shifted back and forth) produced magnetic fields and vice versa.

The two types of energy were integrally connected. Maxwell realized that electricity and magnetism were simply two expressions of a single energy stream and named it electromagnetic energy. When he first published these equations and his discoveries in an 1864 article, physicists instantly recognized the incredible value and meaning of Maxwell’s four equations.

Maxwell continued to work with his set of equations and realized that—as long as the electrical source oscillated at a high enough frequency—the electromagnetic energy waves it created could and would fly through the open air—without conducting wires to travel along. This was the first pre dic tion of radio waves.

He calculated the speed at which these electromagnetic waves would travel and found that it matched the best calculations (at that time) of the speed of light. From this, Maxwell realized that light itself was just another form of electromagnetic radiation. Because electrically charged currents can oscillate at any frequency, Maxwell realized that light was only a tiny part of a vast and continuous spectrum of electromagnetic radiation.

Maxwell predicted that other forms of electromagnetic radiation along other parts of this spectrum would be found. As he predicted, X-rays were discovered in 1896 by Wilhelm Roentgen. Eight years before that discovery, Heinrich Hertz conducted experiments following Maxwell’s equations to see if he could cause electromagnetic radiation to fly through the air (transmit through space in the form of waves of energy). He easily created and detected the world’s first radio waves, confirming Maxwell’s equations and predictions.


Fun Facts: Astronomers have concluded that the most efficient way of making contact with an intelligent civilization orbiting another star is to use radio waves. However, there are many natural processes in the universe that produce radio waves. If we could translate those naturally produced radio waves into sound, they would sound like static we hear on a radio. In the search for intelligent life, astronomers use modern computers to distinguish between a “signal” (possible message) and the “noise” (static).


The Theory of Evolution

Species evolve over time to best take advantage of their surrounding environment, and those species most fit for their environment survive best.

  • Who Discovered it?: Charles Darwi3398n
  • Year of Discovery: 1858

How was it Discovered?

Darwin’s theory of evolution and its concept of survival of the fittest is the most fundamental and important discovery of modern biology and ecology. Darwin’s discoveries are 150 years old and are still the foundation of our understanding of the history and evolution of plant and animal life.

Charles Darwin entered Cambridge University in 1827 to become a priest but switched to geology and botany. He graduated in 1831 and, at age 22, took a position as naturalist aboard the HMS Beagle bound from England for South America and the Pacific.

The Beagle’s three-year voyage stretched into five. Darwin forever marveled at the unending variety of species in each place the ship visited. But it was their extended stop at the Pacific Ocean Galapagos Islands that focused Darwin’s wonder into a new discovery.

On the first island in the chain he visited (Chatham Island), Darwin found two distinct species of tortoise—one with long necks that ate leaves from trees, and one with short necks that ate ground plants. He also found four new species of finches (small, yellow birds common across much of Europe). But these had differently shaped beaks from their European cousins.

The Beagle reached the third Galapagos Island (James Island) in October 1835. Here, right on the equator, no day or season seemed any different than any other.

As he did every day on shore, Darwin hoisted his backpack with jars and bags for collecting samples, a notebook for recording and sketching, and his nets and traps and set off across the frightful landscape through twisted fields of crunchy black lava thrown up into giant ragged waves. Gaping fissures from which dense steam and noxious yellow vapors hissed from deep in the rock blocked his path. The broken lava was covered by stunted, sunburned brushwood that looked far more dead than alive.

In a grove of trees filled with chirping birds, Darwin found his thirteenth and fourteenth new species of finches. Their beaks were larger and rounder than any he’d seen on other islands. More important, these finches ate small red berries.

Everywhere else on Earth finches ate seeds. In these islands, some finches ate seeds, some insects, and some berries! More amazingly, each species of finch had a beak perfectly shaped to gather the specific type of food that species preferred to eat.

Darwin began to doubt the Christian teaching that God created each species just as it was and that species were unchanging. He deduced that, long ago, one variety of finch arrived in the Galapagos from South America, spread out to the individual islands, and then adapted (evolved) to best survive in its particular environment and with its particular sources of food. These findings he reported in his book, A Naturalist’s Voyage on the Beagle.

After his return to England, Darwin read the collected essays of economist Thomas Malthus, who claimed that, when human populations could not produce enough food, the weakest people starved, died of disease, or were killed in the fighting. Only the strong survived. Darwin realized that this concept should apply to the animal world as well.

He blended this idea with his experiences and observations on the Beagle to conclude that all species evolved to better ensure species survival. He called it natural selection.

A shy and private man, Darwin agonized for years about revealing his theories to the public. Other naturalists finally convinced him to produce and publish Origin of Species. With that book, Darwin’s discoveries and theory of evolution became the guiding light of biological sciences.


Fun Facts: Bats, with their ultrasonic echolocation, have evolved the most acute hearing of any terrestrial animal. With it, bats can detect insects the size of gnats and objects as fine as a human hair.


“Microorganisms too small to be seen or felt exist everywhere in the air and cause disease and food spoilage.”

  • Who Discovered it?: Louis Pasteur
  • Year of Discovery: 1856

How was it Discovered?


In the fall of 1856, 38-year-old Louis Pasteur was in his fourth year as Director of Scientific Affairs at the famed Ecole Normale in Paris. It was an honored administrative position. But Pasteur’s heart was in pure research chemistry and he was angry.

Many scientists believed that microorganisms had no parent organism. Instead, they spontaneously generated from the decaying molecules of organic matter to spoil milk and rot meat. Felix Pouchet, the leading spokesman for this group, and had just published a paper claiming to prove this thesis.

Pasteur thought Pouchet’s theory was rubbish. Pasteur’s earlier discovery that microscopic live organisms (bacteria called yeasts) were always present during, and seemed to cause, the fermentation of beer and wine, made Pasteur suspect that microorganisms lived in the air and simply fell by chance onto food and all living matter, rapidly multiplying only when they found a decaying substance to use as nutrient.

Two questions were at the center of the argument. First, did living microbes really float in the air? Second, was it possible for microbes to grow spontaneously (in a sterile environment where no microbes already existed)?

Pasteur heated a glass tube to sterilize both the tube and the air inside. He plugged the open end with guncotton and used a vacuum pump to draw air through the cotton filter and into this sterile glass tube.

Pasteur reasoned that any microbes floating in the air should be concentrated on the outside of the cotton filter as the air was sucked through it. Bacterial growth on the filter indicated microbes floating freely in the air. Bacterial growth in the sterile interior of the tube meant spontaneous generation.

After 24 hours the outside of his cotton wad turned dingy gray with bacterial growth while the inside of the tube remained clear. Question number 1 was answered. Yes, microscopic organisms did exist, floating, in the air. Any time they concentrated (as on a cotton wad) they began to multiply.

Now for question number 2. Pasteur had to prove that microscopic bacteria could not spontaneously generate.

Pasteur mixed a nutrient-rich bullion (a favorite food of hungry bacteria) in a large beaker with a long, curving glass neck. He heated the beaker so that the bullion boiled and the glass glowed. This killed any bacteria already in the bullion or in the air inside the beaker. Then he quickly stoppered this sterile beaker. Any growth in the beaker now had to come from spontaneous generation.

He slid the beaker into a small warming oven, used to speed the growth of bacterial cultures.

Twenty-four hours later, Pasture checked the beaker. All was crystal clear. He checked every day for eight weeks. Nothing grew at all in the beaker. Bacteria did not spontaneously generate. Pasteur broke the beaker’s neck and let normal, unsterilized air flow into the beaker. Seven hours later he saw the first faint tufts of bacterial growth. Within 24 hours, the surface of the bullion was covered.

Pouchet was wrong. Without the original airborne microbes floating into contact with a nutrient, there was no bacterial growth. They did not spontaneously generate.

Pasteur triumphantly published his discoveries. More important, his discovery gave birth to a brand new field of study, microbiology.


Fun Facts: The typical household sponge holds as many as 320 million disease-causing germs.

Doppler Effect

“Sound- and light-wave frequencies shift higher or lower depending on whether the source is moving toward or away from the observer.”

  • Who Discovered it?: Christian Doppler
  • Year of the Discovery: 1848

How was it Discovered?


Austrian-born Christian Doppler was a struggling mathematics teacher—struggling both because he was too hard on his students and earned the wrath of parents and administrators and because he wanted to fully understand the geometry and mathematical concepts he taught. He drifted in and out of teaching positions through the 1820s and 1830s as he passed through his twenties and thirties. Doppler was lucky to land a math teaching slot at Vienna Polytechnic Institute in 1838.

By the late 1830s, trains capable of speeds in excess of 30 mph were dashing across the countryside. These trains made a sound phenomenon noticeable for the first time. Never before had humans traveled faster than the slow trot of a horse. Trains allowed people to notice the effect of an object’s movement on the sounds that the object produced.

Doppler intently watched trains pass and began to theorize about what caused the sound shifts he observed. By 1843 Doppler had expanded his ideas to include light waves and developed a general theory that claimed that an object’s movement either increased or decreased the frequency of sound and light it produced as measured by a stationary observer. Doppler claimed that this shift could explain the red and blue tinge to the light of distant twin stars. (The twin circling toward Earth would have its light shifted to a higher frequency—toward blue. The other, circling away, would shift lower, toward red.)

In a paper he presented to the Bohemian Scientific Society in 1844, Doppler presented his theory that the motion of objects moving toward an observer compresses sound and light waves so that they appear to shift to a higher tone and to a higher frequency color (blue). The reverse happened if the object was moving away (a shift toward red). He claimed that this explained the often observed red and blue tinge of many distant stars’ light. Actually, he was wrong. While technically correct, this shift would be too small for the instruments of his day to detect.

Doppler was challenged to prove his theory. He could n’t with light because telescopes and measuring equipment were not sophisticated enough. He decided to demonstrate his principle with sound.

In his famed 1845 experiment, he placed musicians on a railway train playing a single note on their trumpets. Other musicians, chosen for their perfect pitch, stood on the station platform and wrote down what note they heard as the train approached and then receded. What the listeners wrote down was consistently first slightly higher and then slightly lower than what the moving musicians actually played.

Doppler repeated the experiment with a second group of trumpet players on the station platform. They and the moving musicians played the same note as the train passed. Listeners could clearly hear that the notes sounded different. The moving and stationary notes seemed to interfere with each other, setting up a pulsing beat.

Having proved the existence of his effect, Doppler named it the Doppler Shift. However, he never enjoyed the fame he sought. He died in 1853 just as the scientific community was beginning to accept and to see the value of, his discovery.

The Doppler Effect is one of the most powerful and important concepts ever discovered for astronomy. This discovery allowed scientists to measure the speed and direction of stars and galaxies many millions of light years away. It unlocked mysteries of distant galaxies and stars and led to the discovery of dark matter and of the actual age and motion of the universe. Doppler’s discovery has been used in the research efforts of a dozen scientific fields.

Few single concepts have ever proved more useful. Doppler’s discovery is considered to be so fundamental to science that it is included in virtually all middle and high school basic science courses.



Fun Facts: Doppler shifts have been used to prove that the universe is expanding. A convenient analogy for the expansion of the universe is a loaf of unbaked raisin bread. The raisins are at rest relative to one another in the dough before it is placed in the oven. As the bread rises, it also expands, making the space between the raisins increase. If the raisins could see, they would observe that all the other raisins were moving away from them although they themselves seemed to be stationary within the loaf. Only the dough—their “universe”—is expanding.

The Existence of Molecules

“A molecule is a group of attached atoms. An atom uniquely identifies one of the 100+ chemical elements that make up our planet. Bonding a number of different atoms together makes a molecule, which uniquely identifies one of the many thousands of substances that can exist.”

  • Who Discovered it?: Amedeo Avogadro
  • Year of the Discovery: 1811

How was it Discovered?

2010-11-08-16-23-00-1-amadeo-avogadro-is-noted-for-his-contributions-toIf atoms are the basic building block of each element, then molecules are the basic building blocks of each substance on Earth.

Scientists were stalled by their inability to accurately imagine—let alone detect—particles as small as an atom or a molecule. Many had theorized that some tiny particle (that they called an atom) was the smallest possible particle and the basic unit of each element.

However, the substances around us were not made of individual elements. Scientists were at a loss to explain the basic nature of substances.

In the spring of 1811, 35-year-old college professor Amedeo Avogadro sat in his classroom scowling at two scientific papers laid out on his desk. Avogadro taught natural science classes at Vercelli College in the Italian mountain town of Turin. Twenty-five students sat each day and listened to Professor Avogadro lecture, discuss, and quiz them on whatever aspects of science caught his fancy. This day he read these two papers to his class, claimed that he saw an important mystery in them, and challenged his students to find it.

In the two papers, the English chemist, Dalton, and the French chemist, Gay-Lussaceach described an experiment in which they combined hydrogen and oxygen atoms to create water. Both reported that it took exactly two liters of gaseous hydrogen atoms to combine with exactly one liter of oxygen atoms to produce exactly two liters of gaseous water vapor. Dalton claimed that this experiment proved that water is the combination of two atoms of hydrogen and one atom of oxygen. Gay-Lussac also claimed it proved that a liter of any gas had to contain exactly the same number of atoms as a liter of any other gas, no matter what gas it was.

These studies were heralded as major breakthroughs for chemical study. But from his first reading, Professor Avogadro was bothered by a nagging contradiction. Both Dalton and Gay-Lussac started with exactly two liters of hydrogen and one liter of oxygen. That’s a total of three liters of gas. But they both ended with only two liters of water vapor gas. If every liter of every gas has to have exactly the same number of atoms, then how could all the atoms from three liters of gas fit into just two liters of water vapor gas?

The Turin cathedral bell chimed midnight before the answer struck Avogadro’s mind. Dalton and Gay-Lussac had used the wrong word. What if they had each substituted “a group of attached atoms” for atom?

Avogadro created the word molecule (a Greek word meaning, “to move about freely in a gas”) for this “group of attached atoms.” Then he scratched out equations on paper until he found a way to account for all of the atoms and molecules in Dalton’s and Gay-Lussac’s experiments.

If each molecule of hydrogen contained two atoms of hydrogen, and each molecule of oxygen contained two atoms of oxygen, then—if each molecule of water vapor contained two atoms of hydrogen and one atom of oxygen, as both scientists reported each liter of hydrogen and each liter of oxygen would have exactly the same number of molecules as each of the two resulting liters of water vapor (even though they contained a different number of atoms)!

And so it was that, without ever touching a test tube or chemical experiment of any kind, without even a background in chemistry, Amedeo Avogadro discovered the existence of molecules and created the basic gas law—every liter of a gas contains the same number of molecules of gas.

Avogadro’s discovery (and the related Avogadro’s Number) have become one of the cornerstones of organic and inorganic chemistry as well as the basis for the gas laws and much of the development of quantitative chemistry.

Fun Facts: The small est molecule is the hydrogen molecule—just two protons and two electrons. DNA is the largest known naturally occurring molecule, with over four billion atoms—each containing a number of protons, neutrons, and electrons.

Electrochemical Bonding

Molecular bonds between chemical elements are electrical in nature

  • Who Discovered it?: Humphry Davy.
  • Year of Discovery: 1806

How was it Discovered?

Davy discovered that the chemical bonds between individual atoms in a molecule are electrical in nature. We now know that chemical bonds are created by the sharing or transfer of electrically charged particles—electrons—between atoms. In 1800, the idea that chemistry somehow involved electricity was a radical discovery.250px-Sir_Humphry_Davy,_Bt_by_Thomas_Phillips

Humphry Davy was born in 1778 along the rugged coast of Cornwall, England. He received only minimal schooling and was mostly self-taught. As a young teenager, he was apprenticed to a surgeon and apothecary. But the early writings of famed French scientist Antoine Lavoisier sparked his interest in science.

In 1798 Davy was offered a chance by wealthy amateur chemist Thomas Beddoes to work in Bristol, England, at a new lab Beddoes built and funded. Davy was free to pursue chemistry-related science whims. He experimented with gases in 1799, thinking that the best way to test these colorless creations was to breathe them. He sniffed nitrous oxide (N2O) and passed out, remembering nothing but feeling happy and powerful. After he reported its effect, the gas quickly became a popular party drug under the name “laughing gas.” Davy used nitrous oxide for a wisdom tooth extraction and felt no pain.

Even though he reported this in an article, it was another 45 years before the medical profession finally used nitrous oxide as its first anesthetic.

Davy also experimented with carbon dioxide. He breathed it and almost died from carbon dioxide poisoning. A born showman, movie-star handsome, and always fashionably dressed, Davy delighted in staging grand demonstrations of each experiment and discovery for thrilled audiences of public admirers.

In 1799, Italian Alessandro Volta invented the battery and created the world’s first manmade electrical current. By 1803, Davy had talked Beddoes into building a giant “Voltaic Pile” (battery) with 110 double plates to provide more power. Davy turned his full attention to experimenting with batteries. He tried different metals and even charcoal for the two electrodes in his battery and experimented with different liquids (water, acids, etc.) for the liquid (called an electrolyte) that filled the space around the battery’s plates.

In 1805 Davy noticed that a zinc electrode oxidized while the battery was connected.  That was a chemical reaction taking place in the presence of an electrical current. Then he noticed other chemical reactions taking place on other electrodes. Davy realized that the battery (electric current) was causing chemical reactions to happen.

As he experimented with other electrodes, Davy began to realize the electrical nature of chemical reactions. He tried a wide variety of materials for the two electrodes and different liquids for the electrolyte.

In a grand demonstration in 1806, Davy passed a strong electric current through pure water and showed that he produced only two gasses—hydrogen and oxygen. Water molecules had been torn apart by an electric current. This demonstration showed that an electrical force could tear apart chemical bonds. To Davy, this meant that the original chemical bonds had to be electrical in nature or an electric current couldn’t have ripped them apart.

Davy had discovered the basic nature of chemical bonding. Chemical bonds were somehow electrical. This discovery radically changed the way scientists viewed the formation of molecules and chemical bonds.

Davy continued experiments, passing electrical currents from electrode to electrode through almost every material he could find. In 1807 he tried the power of a new battery with 250 zinc and copper plates on caustic potash and isolated a new element that burst into brilliant flame as soon as it was formed on an electrode. He named this newly discovered element; PotassiumA month later he isolated Sodium. Davy had used his grand discovery to discover two new elements.

Davy’s discovery started the modern field of electrochemistry and redefined science’s view of chemical reactions and how chemicals bond together. Not to mention that he discovered the two new very important elements, Potassium, and Sodium.

Fun Facts: A popular use of electrochemical bonding is in cookware. The process unites the anodized surface with the aluminum base, creating a nonporous surface that is 400 percent harder than aluminum.


An atom is the smallest particle that can exist of any chemical element.

  • Who discovered it?: John Dalton
  • Year of Discovery: 1802

How was it Discovered?


In the fifth century B.C.Leucippus of Miletus and Democritus of Abdera theorized that each form of matter could be broken into smaller and smaller pieces. They called that smallest particle that could no longer be broken into smaller pieces an atomGalileo and Newton both used the term atom in the same general way. Robert Boyle and Antoine Lavoisier were the first to use the word element to describe one of the newly discovered chemical substances. All of this work, however, was based on general philosophical theory, not on scientific observation and evidence.

John Dalton was born in 1766 near Manchester, England, and received a strict Quaker upbringing. With little formal education, he spent 20 years studying meteorology and teaching at religious, college-level schools. Near the end of this period, Dalton joined and presented a variety of papers to the Philosophical Society. These included papers on the barometer, the thermometer, the hygrometer, rainfall, the formation of clouds, evaporation, atmospheric moisture, and dewpoint. Each paper presented new theories and advanced research results.

Dalton quickly became famous for his innovative thinking and shifted to science research full time. In 1801 he turned his attention from the study of atmospheric gasses to chemical combinations. Dalton had no experience or training in chemistry. Still, he ploughed confidently into his studies.

By this time almost 50 chemical elements had been discovered—metals, gasses, and nonmetals. But scientists studying chemistry were blocked by a fundamental question they couldn’t answer: How did elements actually combine to form the thousands of compounds that could be found on Earth? For example, how did hydrogen (a gas) combine with oxygen (another gas) to form water (a liquid)? Further, why did exactly one gram of hydrogen always combine with exactly eight grams of oxygen to make water—never more, never less?

Dalton studied all of the chemical reactions he could find (or create), trying to develop a general theory for how the fundamental particle of each element behaved. He compared the weights of each chemical and the likely atomic structure of each element in each compound. After a year of study, Dalton decided that these compounds were defined by simple numerical ratios by weight. This decision allowed him to deduce the number of particles of each element in various well-known compounds (water, ether, etc.).

Dalton theorized that each element consisted of tiny, indestructible particles that were what combined with other elements to form compounds. He used the old Greek word, atom, for these particles. But now it had a specific chemical meaning.

Dalton showed that all atoms of any one element were identical so that any of them could combine with the atoms of some other element to form the known chemical compounds. Each compound had to have a fixed number of atoms of each element. Those fixed ratios never changed. He deduced that compounds would be made of the minimum number possible of atoms of each element. Thus water wouldn’t be H4O2 because H2O was simpler and had the same ratio of hydrogen and oxygen atoms.

Dalton was the first to use letter symbols (H, O, etc.) to represent the various elements. Scientists readily accepted Dalton’s theories and discoveries, and his concepts quickly spread across all Western science. We still use his concept of an atom today.

“Since atoms are the key to understanding chemistry and physics, Dalton’s discovery of the atom ranks as one of the greatest turning points in science. Because of this discovery, Dalton is often called the father of modern physical science.”


A medication used during surgery that causes loss of awareness of pain in patients.
  • Who Discovered it?: Humphry Davy
  • Year of Discovery: 1801

How was it Discovered?


The word anesthesia, from the Greek words, meaning “lack of sensation,” was coined by Oliver Wendell Holmes (father of the supreme court chief justice by the same name) in 1846.

However, the concept of anesthesia is millennia old. Ancient Chinese doctors developed acupuncture techniques that blocked the transmission of pain sensations to the brain. Ancient Romans and Egyptians used Mandrake (the root of the Mandragora plant) to induce unconsciousness. European doctors in the middle ages also favored mandrake. Inca shamans chewed coca leaves and spit the juice (cocaine) into wounds and cuts to numb their patients’ pain.

Three nineteenth-century scientists each laid claim to the medical discovery of modern anesthesia. None of them deserves the credit because Humphry Davy had already earned that distinction.

Scottish obstetrician Sir Young Simpson was the first to experiment with chloroform. He observed that patients who inhaled a few breaths of the gas (a wad of cotton soaked in chloroform was placed under the nose) quickly became relaxed and calm, and were soon unconscious. His use of the drug drew no attention until, in 1838, Queen Victoria asked for Simpson and his chloroform for the birth of her seventh child.

Chloroform’s greatest use came during the American Civil War. Southern cotton was often traded in England for medicines—including chloroform—that became a staple of battlefield operating tents for Southern doctors. After the war, chloroform continued to enjoy some popularity—especially in the South—until synthetic drugs were developed in the early twentieth century.

Georgia physician Crawford Long was the first to use ether during an operation. In 1842 he removed a neck tumor from James Venable, a local judge. The operation went perfectly and the judge felt no pain. But Long never bothered to publicize his success.

Two years later Boston dentist Horace Wells took up the notion of using ether to dull operation pain. Wells mistakenly turned off the gas too soon. His patient sat up and screamed. The crowd of observing doctors scoffed and called Well’s claims for ether a hoax.

One year later (1845), Boston dentist William Morton gave ether another try. Morton’s operation went flawlessly. Only after Morton’s second successful public operation with ether, and only after he had published several articles touting the glories of ether, did doctors across America—and then Europe—turn to ether as their primary anesthetic.

However, none of these men was the first to discover modern medical anesthesia. In 1801, English scientist Humphry Davy was experimenting with gasses when he combined nitrogen and oxygen to produce nitrous oxide. Davy tested the resulting colorless gas and eventually took several deep breaths. He reported a soaring euphoria that soon passed into an uncontrollable outburst of laughter and sobbing until he passed out (it made him unconscious).

Davy named the stuff laughing gas and noted its tendency to make him unaware of pain. Davy recommended it for use as an anesthetic during medical and dental procedures. Even though doctors took no note of his discovery, Davy’s work is the first scientific identification and testing of an anesthetic.

Anaesthesia created safe surgery and made many medical and dental operations practical and plausible. The trauma suffered by patients from the pain of operation was often so dangerous that it kept doctors from attempting many surgical procedures. That pain also kept many severely ill patients from seeking medical help.

Anesthesia eliminated much of the pain, fear, anxiety, and suffering for medical and dental patients during most procedures and gave the medical profession a chance to develop and refine the procedures that would save countless lives.

“Anesthesiology is now a major medical specialty and an important position in every operating room. While it is probable that new drugs and new types of anesthesia will be developed in the coming decades, this important aspect of medicine will be with us forever.”


Fun Fact: The common phrase “biting the bullet” dates from the days before anaesthetics were available on the battlefield. Biting on the soft lead of a bullet absorbed the pressure of the bite without damaging a soldier’s teeth.


Plants use sunlight to convert carbon dioxide in the air into new plant matter.

  • Who discovered it?: Jan Ingenhousz
  • Year of Discovery: 1779


How was it discovered?

Photosynthesis is the process that drives plant production all across Earth. It is also the process that produces most of the oxygen that exists in our atmosphere for us to breathe. Plants and the process of photosynthesis are key elements in the critical (for humans and other mammals) planetary oxygen cycle.

When Jan Ingenhousz discovered the process of photosynthesis, he vastly improved our basic understanding of how plants function on this planet and helped science gain a better understanding of two important atmospheric gases: oxygen and carbon dioxide. 

Modern plant engineering and crop sciences owe their foundation to Jan Ingenhousz’s discovery.

Jan Ingenhousz was born in Breda in the Netherlands in 1730. He was educated as a physician and settled down to start his medical practice back home in Breda.

In 1774 Joseph Priestley discovered oxygen and experimented with this new, invisible gas. In one of these tests, Priestley inserted a lit candle into a jar of pure oxygen and let it burn until all oxygen had been consumed and the flame went out. Without allowing any new air to enter the jar, Priestley placed mint sprigs floating in a glass of water in the jar to see if the mint would die in this “bad” air. But the mint thrived. After two months, Priestley placed a mouse in the jar. It also lived proving that the mint plant had restored oxygen to the jar’s air. But this experiment didn’t always work. Priestley admitted that it was a mystery and then moved on to other studies.

In 1777, Ingenhousz read about Priestley’s experiments and was fascinated. He could focus on nothing else and decided to investigate and explain Priestley’s mystery. Over the next two years, Ingenhousz conducted 500 experiments trying to account for every variable and every possible contingency. He devised two ways to trap the gas that a plant produced. One was to enclose the plant in a sealed chamber. The other was to submerge the plant.

Ingenhousz used both systems but found it easier to collect and study the gas collected under water as tiny bubbles. Every time he collected the gas that a plant gave off, he tested it to see if it would support a flame (have oxygen) or if it would extinguish a flame (be carbon dioxide).

Ingenhousz was amazed at the beauty and symmetry of what he discovered. Humans inhaled oxygen and exhaled carbon dioxide. Plants did just the opposite sort of. Plants in sunlight absorbed human waste carbon dioxide and produced fresh oxygen for us to breathe. Plants in deep shade or at night (in the dark), however, did just the opposite. They acted like humans, absorbing oxygen and producing carbon dioxide.

After hundreds of tests, Ingenhousz determined that plants produced far more oxygen than they absorbed. Plants immersed in water produced a steady stream of tiny oxygen bubbles when in direct sunlight. Bubble production stopped at night. Plants left for extended periods in the dark gave off a gas that extinguished a flame. When he placed the same plant in direct sunlight, it produced a gas that turned a glowing ember into a burning inferno. The plant again produced oxygen.

Ingenhousz showed that this gas production depended on sunlight. He continued his experiments and showed that plants did not produce new mass (leaf, stem, or twig) by absorbing matter from the ground (as others believed). The ground did not lose mass as a plant grew. Ingenhousz showed that new plant growth must come from sunlight. Plants captured carbon from carbon dioxide in the air and converted it into new plant matter in the presence of sunlight.

Ingenhousz had discovered the process of photosynthesis. He proved that plants created new mass “from the air” by fixing carbon with sunlight. In 1779 he published his results in Experiments Upon Vegetables. The name photosynthesis was created some years later and comes from the Greek words meaning “to be put together by light.”

Fun Facts: Some species of bamboo have been found to grow at up to 91 cm (3 ft.) per day. You can almost watch them grow!