| Scientist | Known For |
| Thales (c.624 B.C.--c.547 B.C) | Thought all things came from water.
Brought geometry and astronomy to Greece. |
| Anaximander (c.610 B.C--c.546 B.C.) | First to depict inhabited Earth on a chart.
Evolutionary theory: all land animals evolved from fish-like ancestors.
Earth floats freely; cylindrical. |
| Pythagoras (c.570 B.C.--c.490 B.C.) | Thought numbers were divine; all things made up of numbers.
Central Fire. |
| Leucippus | Discovered the atom. |
| Aristotle (384 B.C.--322 B.C.) | First to attempt classification and understanding of living things; biology. |
| Aristarchus (c.310 B.C.--c.230 B.C.) | Made first mathematically sound attempt at measuring the cosmos.
Geocentric model.
Bowl-shaped sundial; skaphe. |
| Archimedes (287 B.C.--212 B.C.) | Invented war devices; catapult.
Discoveries in math and geometry. |
| ibn al-Haitham (c.965--c.1040) | Islamic mathematician, theorist, experimenter.
Claimed objects emanated light. |
| Copernicus (1473--1543) | Heliocentric model.
Circular orbits. |
| Galileo Galilei (1564--1642) | First to observe sunspots, rotation of Sun, mountains and depressions on moon, Jupiter's moons.
Proved heliocentric model.
Designed thermometer, geometric and military compass.
Founded scientific study of motion and gravity. |
| Johannes Kepler (1571--1630) | Laws of planetary motion.
Elliptical orbits. |
| Antony van Leeuwenhoek (1632--1723) | First to see one-celled plants and animals, bacteria, blood cells, spermatozoa; animalcules.
Observed circulation.
Improved microscopes. |
| Isaac Newton (1642--1727) | Differential calculus.
Three laws of motion.
Theory of universal gravitation. |
| Joseph Priestley (1733--1804) | Contributions to language, history, theology, education, natural philosophy.
Had one of the best-equipped chemical labs in the world.
Generated air; "dephlogisticated air."
Discovered photosynthesis. |
| Humphry Davy (1778--1829) | Discovered six chemical elements.
Developed anesthetic; nitrous oxide ("laughing gas").
Discovered elements cannot be decomposed by chemical reactions.
Invented miner's safety lamp. |
| Charles Babbage (1792--1852) | Difference Engine (failed).
Analytical Engine (incomplete).
Worked with Ada Lovelace. |
| Ada Byron Lovelace (1815--1852) | Created first program.
Worked with Charles Babbage. |
| Charles Darwin (1809--1882) | Theory of evolution; natural selection. |
| Gregor Mendel (1822--1884) | Laws of heredity. |
| Dmitri Mendeleev (1834--1907) | Periodic law; periodic table of the elements.
Economic development of Russia. |
| Marie Curie (1867--1934) | Discovered the elements polonium and radium.
First woman to win a Nobel Prize. |
| Max Planck (1858--1947) | Discovered quantum physics. |
| Guglielmo Marconi (1874--1937) | Wireless communication; telegraphy.
First to send wireless signals across the Atlantic.
Used long-wave, then short wavelengths. |
