Category: Impactful Scientists

James Lind

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James Lind portrait
James Lind

James Lind (1716 – 1794) was a Scottish doctor who is famous for his medical insight that eating citrus fruits will prevent and cure scurvy.  He instituted other recommendations which stressing the importance of ventilation of ships and hygiene to the Royal Navy.

Lind was born in Edinburgh and began his education as an apprentice at the College of Surgeons at Edinburgh University before entering the Navy as a surgeons mate.   In 1747 he had become surgeon of the 50 gun vessel HMS Salisbury. 

As surgeon he carried out experiments, or clinical trials, to discover the cause of scurvy.  Scurvy was a disease that was extremely deadly to sailors during the Age of Exploration.  It is estimated that over 2 millions sailors were killed by the disease.  Its symptoms weakness and fatigue, muscle soreness, loose teeth, bleeding gums and hemorrhages.  It is caused by a lack of Vitamin C in the diet which is why citrus fruits prevent and cure it.

To carry out his experiment, Lind selected twelve men from his ship who suffered from scurvy and divided them into two groups of six, feeding each group a different diet.  One of the groups contained citrus fruit, such as lemons and oranges, and this was the group that showed remarkable recovery results.  This can be considered one of the first reported, controlled clinical trials in history.  In 1753 he published A Treatise of the Scurvy to little fanfare.  Lind recognized the importance of citrus friends in his treatise but he believed that there were multiple causes and hence many cures for the disease.   He notes that the group that had the oranges and lemons recovered yet he is unclear on his recommendations to scurvy’s cure.

Lind continued to work on improving the diet and hygene of sailors.  In 1762 Lind published an Essay on the Most Effectual Means of preserving the Health of Seamen rehashing some of his recommendations of his first book while adding further remarks on improving sailors heath.  It wasn’t until 40 years later that the Navy mandated a supply of lemon juice on all ships, and with the scurvy virtually disappeared. Lind continued to do work on typhus, tropical disease, and other areas until he died in 1794.

Theodor Schwann

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Theodor Schwann portrait
Theodor Schwann

Theodor Schwann (1810 – 1882) was a German physician and physiologist who proposed the cellular nature of all living things.  Along with Matthias Schleiden, Schwann laid down the foundation to Cell Theory.

Schwann was born in Neuss, Germany, attended a Jesuit school in Cologne, enrolled in the University of Bonn, transferred the the University of Wurzburg for clinical training in medicine before he finally moved the the University of Berlin where he obtained his M.D. degree.  Much of his moving involved him following physiologist Johannes Muller, a leading physiologist of his time.

After he graduated he began to make a series of discoveries.  In 1835 he discovered the enzyme Pepsin.  Next he performed experiments with yeast and fermentation.  He successfully demonstrated that fermentation was an organic process; that living yeast was necessary to produce more yeast.

Schwann’s most important work was in the development of Cell Theory.  He began by taking the idea that all plants are made from cells and extended them to animals.  In 1838 Schleiden published Contributions to our Knowledge of Phytogenesis, outlining his theories of the roles of cells in plant development.  This influenced Schwann and the next year he published Microscopical Researches into the Accordance in the Structure and Growth of Animals and Plants, a landmark work where he proposed his own Cell Theory.  In it he exclaimed ” “All living things are composed of cells and cell products”, extending Schleiden’s idea that new plant cells are formed from old plant cells to the domain of animals.   He also coined the term “metabolism” to describe chemical reactions taking place within the cell.

Cell Theory and his work on yeast and fermentation provided strong evidence against the idea of spontaneous generation – the idea that living organisms could develop from nonliving matter.  This won him tremendous respect from his peers.  In 1879 Schwann was elected to both the Royal Society and to the French Academy of Science.  He died three years later.

Matthew Maury

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Matthew Maury portrait
Matthew Maury

Matthew Maury (1806 – 1873) was an American Naval officer and oceanographer.  He is credited with the moniker “Father of Modern Oceanography” thanks to the comprehensive book on oceanography he published in 1855, The Physical Geography of the Sea.

Maury was born into a Huguenot family in Virginia but had moved to Tennessee by the time he turned five.  His brother John was a Navy officer and Matthew was determined to follow suit.  He obtained a naval appointment at age 19 from Tennessee Representative Sam Houston.  He immediately began studying the sea on a four-year voyage aboard the Vincennes that began in 1826.  It was the first US Naval warship to circumnavigate the globe.  Sadly, his seafaring days came to an abrupt end at the age of 33 after his leg was maimed in a stagecoach accident.  Henceforth he would devote his time to studying the ocean.

In 1842 Maury was placed as head of the Depot of Charts and Instruments in Washington DC, which offered him a tremendous amount of maritime data in terms of log books and various other records.  He would eventually turn this institution into the United States Naval Observatory and become its first superintendent.

In 1855 he published the first modern oceanography textbook, The Physical Geography of the Sea, describing the winds, currents, climate, and physical geography over the worlds oceans.  That same year Maury proposed sea lanes in his book Sailing Directions.  This idea was taken up by the major shipping companies to the benefit of lives and dollars saved.  He also sent out survey ships to take depth readings on the Atlantic Ocean’s floor, which revealed the Mid-Atlantic ridge.  His books and his surveys helped to prove the feasibility of laying a first transatlantic cable, which occurred in July 1866.

The American Civil War interrupted his career, sending him to Europe and then to Mexico before he finally returned to Virginia where he took the post of professor of meteorology at the Virginia Military Institute.  He stayed there until his death in 1873.

Henry Cavendish

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Henry Cavendish portrait
Henry Cavendish

Henry Cavendish (1731 – 1810) was one of the great experimental and theoretical chemist and physicist of the 18th century.  So meaningful were his contributions to science that James Clerk Maxwell named the University of Cambridge’s physics laboratory in his honor after he founded it in 1874.

Henry was born in Nice, France, due to his family traveling at the time of his birth.  He was educated in a private school in London then attended the University of Cambridge in 1748 where he stayed for three more years.  His father, Lord Charles Cavendish, was involved with members of the Royal Society of London and took Henry to meetings in the last 1750s.  By 1760 Henry was became an elected member of the Royal Society and from there on lived a life dedicated to science.

His interest and achievements in science were vast and wide ranging.  He began his work at the Royal Society by heading a committee to review the society’s meteorological instruments.  This initiated his research in chemistry and in particular gas chemistry.  His is credited with being the first person to isolate hydrogen (which he termed “inflammable air”), to correctly calculate its density, and determine that it was contained in water in a two to one proportion.  As with most scientists of his time, Henry also experimented with electricity.  He wrote many papers on electricity for the Royal Society but most of his experiments did not become known until many years after his death.

He was known for his extremely careful and accurate measurements.  This quality came in handy when it came time for him to measure the composition of the atmosphere and the density of the Earth.  Both measurements he obtained compare very nicely with the values accepted today.

Henry Cavendish amassed incredible wealthy throughout his life.  He used his wealthy mainly in the pursuit of science as he was not very sociable.  It is thought that he had Asperger syndrome, a form of autism.  He died in 1810 as one of the wealthiest men in Britain.

Heinrich Hertz

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Heinrich Hertz
Heinrich Hertz

Heinrich Hertz (1857 – 1894) was a German who lived a short yet impactful life.  He was interested in meteorology and assisted in making advances in weather forecasting.  He also conducted groundbreaking research in electromagnetic waves, making him the first person to conclusively prove James Clerk Maxwell’s theory of electromagnetism.

Hertz was born in Hamburg into a wealthy and affluent family.  He showed early aptitude in the sciences and went on the receive his PhD from the University of Berlin in 1880.  He was able to study under the physicist and physician Hermann von Helmholtz, whom he became an assistant to in his post-doctorate studies.  In 1885, Hertz obtained a full time professorship at the University of Karlsruhe.

During his time studying at the University of Berlin Helmholtz encouraged the university’s Philosophy Department to offer a prize to anyone who could solve the problem of whether electricity moves with inertia.  Hertz showed that it did through a series of clever experiments and won the prize.  Impressed by his work and capabilities, Helmholtz then asked Hertz to compete for a different prize offered by the Berlin Academy: verifying Maxwell’s theory of electromagnetism.  He declined to work on this problem after he decided it would be too difficult and time consuming, instead electing to establish his reputation by doing work less tedious.

Six years later Hertz was working at the University of Karlsruhe and decided it was time to return to experimental physics. After several months of experiments some breakthroughs began to emerge.  In November 1886 Hertz devised an experiment in the effects of electromagnetic waves were observed.  They were originally called Hertzian waves, but were later renamed radio waves.  These experiments also allowed Hertz to report on the photoelectric effect which would soon be explained by Albert Einstein.

Hertz successful scientific career was cut short becoming very ill and eventually passed away at the age of 36. The SI unit for frequency – hertz – was named in his honor in 1960, replacing the term “cycles per second.”

Gregor Mendel

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Gregor Mendel portrait
Gregor Mendel

Gregor Mendel (1822 – 1884) was a German-speaking, Augustinian monk who did pioneering work on genetics.  His claim to fame however, was posthumous.  Mendel’s initial work was more or less unknown while he was alive and went unnoticed until it was rediscovered 50 years after death.

Mendel was born in the Austrian Empire in what is now present day Czech Republic.  During his childhood he worked on the family farm until he was sent to school at age 11.  However money was tight for him and his family and financial struggles weighted on his decision to join the monastery.  He joined the Augustinian Saint Thomas’ Abbey in Brünn and began his theological studies.  Mendel was always interested in more than just is theological studies and under a sponsorship he sent to study for two years at the University of Vienna to receive a broader education in the sciences.

When Mendel returned from the University of Vienna he began to carry out experiments on plants in the monastery’s experimental gardens.  He chose the common pea and began his experiments in 1856.  He identified seven traits that seemed to be inherited independently of other traits.  Mendel tested over 28,000 pants in the eight years of experimentation and was able to generalize a few laws of inheritance from his results.

His first law, the Law of Segregation, states that allele pairs (one form of a gene) segregate during gamete (sex cells: sperm or egg) formation.  Stated differently: each organism inherits at least two alleles for each trait but only one of these alleles are randomly inherited when the gametes are produced.  His second law, the Law of Independent Assortment, states the allele pairs separate independently during the formation of gametes.  His third law, the Law of Dominance, states that when two alleles of a pair are different, one will be dominate while the other will be recessive.

Mendel did various other experiments in biology and in other areas of science but the burdens of his administrative duties became too great and he stopped going his scientific studies.  He presented his work a handful of other people but nobody at the time realized the significance of his work.  The conventional wisdom was that there was a general blending of heritable traits rather than Mendel’s particulate inheritance of traits, where traits are passed in discrete packets.  Mendel’s work was rediscovered by three botanists each working independently in 1900 – Hugo DeVries, Carl Correns and Erich von Tschermak.  They gave priority to his work as well as confirmation to their own research.

Pierre de Fermat

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Pierre de Fermat
Pierre de Fermat

Pierre de Fermat (1607 – 1665) was a French mathematician whose mathematical work lead to the development of probability and statistics, the infinitesimal calculus, and of analytic geometry. He may be best know for his famous Fermat’s Last Theorem, a mathematical problem that went unsolved for centuries before it was finally solved by British mathematician Andrew Wiles in 1994.

Fermat was born in Beaumont-de-Lomagne, France, attended the University of Orleans in 1623 where he studied law despite showing an early interest in mathematics.  He received the title of councillor at the High Court of Judicature in Toulouse in 1631 and held this position for the rest of his life.

In the 1630s Fermat began some of his pioneering work in analytic geometry.  His work was circulated around in manuscript form and he showed to how find maximum point, minimum point, and tangents to curves.  He found techniques that were equivalent to differentiation and integral calculus.  These techniques were helpful to Isaac Newton and Gottfried Wilhelm Leibniz when they formulated their theories of calculus.

Along with his pioneering work in analytic geometry and laying the groundwork for the invention of calculus, Fermat had a tremendous contribution to number theory – a branch of mathematics devoted to the study of integers.   His study of Pell’s equation, perfect numbers, amicable numbers, and prime numbers ultimately led to the discovery of a new set of numbers that would be named after him: Fermat numbers.

The work he is best known for is called Fermat’s Last Theorem.  While working on number theory he had scribbled in the margin on a text that he had discovered a proof for an equation, but that the proof was too large for him to fit in the margin.  For over 350 years mathematicians were unable to obtain the proof until his theorem was finally proven in 1994 by Andrew Wiles.

Abu Ja’far Muhammad ibn Musa al-Khwarizmi

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Abu Ja'far Muhammad ibn Musa al-Khwarizmi
Abu Ja’far Muhammad ibn Musa al-Khwarizmi

Abu Ja’far Muhammad ibn Musa al-Khwarizmi (780 – 850) was one of the most influential medieval Arab mathematicians.  He made two remarkable contributions to mathematics – introducing our modern number system into western Europe, the Hindu-Arabic numeral system, and was a pioneer of early algebra.

Al-Khwarizmi lived in Persia and worked in the House of Wisdom under the caliphate of Al-Ma’num.  The House of Wisdom was a public academy, research institution, and intellectual center in Baghdad that acquired and translated scientific, mathematical, and philosophical treatises, particularly those of ancient Greece.  They also published original work, two of which Al-Khwarizmi is most famous for.

Around 820 Al-Khwarizmi published On the Calculation with Hindu Numerals.  Al-Khwarizmi quickly realized the ease of use and efficiency of this decimal numeral system and the popularity of his book is largely responsible for spreading Hindu-Arabic numeral system throughout Europe.  It was Latinized Algoritmi de numero Indorum, and Al-Khwarizmi came to be know in Latin as Algoritmi.  From his name we derived the term algorithm.

About a decade later Al-Khwarizmi published his other famous treatise, The Compendious Book on Calculation by Completion and Balancing.  In it he published the first know linear and quadratic equations. In doing so he revealed the techniques of algebra to the mathematical world.  The term algebra is derived from al-jabr, one of the operations he used to solve his quadratic equation.

Al-Khwarizmi’s work and impact wasn’t immediately felt in Europe as it took until around the 12th century for his work to be translated and spread into Europe.  His original manuscripts have been lost, probably when The House of Wisdom was destroyed during the siege of Baghdad in 1258.  Only his Latin translations survive.  However his popularization of our modern numerical system, his pioneering work in mathematics and early algebra, as well as his other lesser know works in astronomy cement his legacy as one of the most influential scientists of the medieval era.

Charles Darwin

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Charles Darwin portrait
Charles Darwin

Charles Darwin (1809 – 1882) was an English naturalist and biologist who changed the way we think about life on this planet.  In 1859 he published his famous book On the Origins of Species, making the beginning of evolutionary biology and cementing his legacy as the most influential biologist in history.

Charles Darwin was born in Shrewsbury, England, the fifth of six children to his father Robert Darwin and mother Susan Wedgwood.  He attended the University of Edinburgh Medical School but quickly neglected his studies and his father sent him to Christ College, Cambridge with the intentions to have him join the clergy.  While at those university’s Darwin learned much in the intellectual environment, but little on the topics he was sent to study for.  However he was exposed to many free thinkers and a variety of ideas in science, particularly biology and geology.

Darwin was able to put these ideas into practice when he traveled the globe from 1831 – 1836 on the HMS Beagle.  It was during and after this trip that he was able to gather a substantial amount of evidence and privately begin to formulate his ideas on evolution by natural selection.  Upon Darwin’s return from the trip he was immediately received as a celebrity scientists in British circles and had cemented his career as a scientist.

Over the next twenty years Darwin continued to amass evidence to the original framework that he developed on his Beagle voyage.  He was even reluctant to publish his work, in fear of retaliation from the Catholic Church.  However he read a letter by Alfred Russell Wallace describing natural selection in similar terms to his and this motivated Darwin to get to work in publishing his work.  On July 1, 1858 both Darwin and Wallace presented a joint presentation to the Linnean Society presenting their work on natural selection.  It received little attention due to a lack of evidence.

For the next fourteen months Darwin continued to work on his book, and on November 24, 1859 On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life was published and immediately sold out of its 1,250 copies.  This book was the culmination of Darwin’s accumulation of evidence over the decades.

By the time of Darwin’s death in 1882 most scientists had accepted evolution as a fact. That is a powerful testament to how convincing his arguments and evidence was and is why he is regarded as one of the most influential scientists of all time.

Charles Lyell

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Charles Lyell portrait
Charles Lyell

Charles Lyell (1797 – 1875) was a Scottish geologist who popularized and created the general acceptance of James Hutton’s concept of uniformitarianiam.  Uniformitarianiam is the idea that physical features of the Earth were transformed by slow, gradual forces such as erosion and sedimentation which are still at work today. 

Lyell was born into a family of wealth, growing up in an estate house with plenty of good farmland.  His father was a botanist who exposed him to nature at an early age.  Lyell attended Exeter College, Oxford in 1816 where his interest in geology was stimulated by lectures he heard by William Buckland – a man known for attempting to reconcile the biblical flood with geological observations.  By 1823 he was elected to the Geological Society of London. 

By the 1830s Lyell was ready to publish some books on geology and his first book published turned out to be his most famous and most influential book.  Principles of Geology was published in three volumes from 1830 – 1833.  In this book he used the concept of uniformitarianism to explain the Earths features.  This was a very different concept from the conventional wisdom of the day, catastrophism, which stressed sudden, quick, and violent events.  “The present is the key to the past” was the motto of his book.  It means that all of the observable processes present today can be used to describe those of the unobservable the past.  

Charles Darwin read Lyell’s work while on the Beagle, and it heavily influenced his thinking.  As Lyell saw that geological forces active today were also active in the past, Darwin saw that biological forces active today were also active in the past.  The slow, gradual change of a species from generation to generation is what led to speciation, a position on which Lyell gradually came to accept over time, offering a lukewarm endorsement of Darwin’s evolution by natural selection in his Antiquity of Man in 1863.