The Inventions of Galileo Galilei

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Galileo Galilei The Law of the Pendulum

Law of the Pendulum
Galileo Galilei watching a chandelier swing back and forth at the Cathedral of Pisa. Fresco by Luigi Sabatelli (1772-1850)

 Italian mathematician, astronomer, physicist and inventor Galileo Galilei lived from 1564 to 1642. Galileo discovered the "isochronism of the pendulum" aka the "law of the pendulum". Galileo demonstrated at the Tower of Pisa that falling bodies of different weights descend at the same rate. He invented the first refracting telescope, and used that telescope to discover and document Jupiter's satellites, sunspots, and craters on the Earth's moon. He is considered to be the "Father of the Scientific Method".

Galileo Galilei The Law of the Pendulum

The painting above depicts a  young twenty year old Galileo observing a lamp swinging from a cathedral ceiling. Believe it or not Galileo Galilei was the first scientist to observe how long it took any object suspended from a rope or chain (a pendulum) to swing back and forth. There were no wrist watches at that time, so Galileo used his own pulse as a time measurement. Galileo observed that no matter how big the swings were, as in when the lamp was first swung, to how small the swings were as the lamp returned to a standstill, the time it took for each swing to complete was exactly the same.

Galileo Galilei had discovered the law of the pendulum, which gained the young scientist considerable notoriety in the academic world. The law of the pendulum would later be used in the construction of clocks, as it could be used to regulate them.

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Proving Aristotle Was Wrong

tower of pisa
Galileo Galilei performs his legendary experiment, dropping a cannonball and a wooden ball from the top of the Leaning Tower of Pisa, circa 1620. This was designed to prove to the Aristotelians that objects of different weights fall at the same speed. Hulton Archive/Getty Images

While Galileo Galilei was working at the University of Pisa, there was a popular discussion occurring about a long dead scientist and philosopher called Aristotle. Aristotle believed that heavier objects fell faster than lighter objects. Scientists in Galileo's time still agreed with Aristotle. However, Galileo Galilei did not agree and set up a public demonstration to prove Aristotle wrong.

As depicted in the illustration above, Galileo used the Tower of Pisa for his public demonstration. Galileo used a variety of balls of different sizes and weights, and dropped them off of the top of the Tower of Pisa together. Of course, they all landed at the same time since Aristotle was wrong. Objects of different weights all fall to earth at the same speed.

Of course, Gallileo's smug reaction to being proven right won him no friends and he was soon forced to leave the University of Pisa.

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The Thermoscope


By 1593 after his father's death, Galileo Galilei found himself with little cash and lots of bills, including the dowry payments for his sister. At that time, those in debt could be placed in prison.

Galileo's solution was to start inventing in hopes of coming up with that one product which everyone would want. Not much different from the thoughts of inventors today.

Galileo Galilei invented a rudimentary thermometer called the thermoscope, a thermometer which lacked a standardized scale. It was not a big success commecially.

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Galileo Galilei - Military and Surveying Compass

Galileo military compass
Galileo's geometrical and military compass in Putnam Gallery - thought to have been made in. 1604 by his personal instrument-maker Marc'Antonio Mazzoleni. CC BY-SA 3.0

In 1596, Galileo Galilei made headway into his debtor's problems with the successful invention of a military compass used to accurately aim cannonballs. A year later in 1597, Galileo modified the compass so that it could be used for land surveying. Both inventions earned Galileo some well-needed cash.

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Galileo Galilei - Work With Magnetism

Armed lodestones, used by Galileo Galilei in his studies on magnets between 1600 and 1609, iron, magnetite and brass,. Getty Images

The photo above is of the armed lodestones, used by Galileo Galilei in his studies on magnets between 1600 and 1609. They are made of iron, magnetite and brass. A lodestone by definition is any naturally magnetized mineral, able to be used as a magnet. An armed lodestone is an enhanced lodestone, where things are done to make the lodestone a stronger magnet, such as combining and placing additional magnetic materials together. 

Galileo's studies in magnetism began after the publication of William Gilbert's De Magnete in 1600. Many astronomers were basing their explanations of planetary motions on magnetism. For example Johannes Kepler, believed that the Sun was a magnetic body, and the motion of the planets was due to the action of the magnetic vortex produced by the Sun's rotation and that the Earth's ocean tides were also based on the magnetic pull of the moon.

Gallileo disagreed but never the less spent years conducting experiments on magnetic needles, magnetic declination, and the arming of magnets.. 

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Galileo Galilei - First Refracting Telescope

Gallileo telescope
Galileo's telescope, 1610. Found in the collection of the Museo Galileo, Florence. Fine Art Images/Heritage Images/Getty Images

In 1609, during a holiday in Venice Galileo Galilei learnt that a Dutch spectacle-maker had invented the spyglass (later renamed the telescope), a mysterious invention that could make distant objects appear closer.

The Dutch inventor had applied for a patent, however, much of the details surrounding the spyglass were being kept hush-hush as the spyglass was rumored to hold a military advantage for Holland.

Galileo Galilei - Spyglass, Telescope

Being a very competitive scientist, Galileo Galilei set out to invent his own spyglass, despite never having seen one in person, Galileo only knew what it could do. Within twenty-four hours Galileo had built a 3X power telescope, and later after a bit of sleep built a 10X power telescope, which he demonstrated to the Senate in Venice. The Senate praised Galileo publicly and raised his salary.