Stevin, Simon (1548-1620)
Belgian-born Dutch mathematician and engineer
Simon Stevin (Latinized to Stevinus, as was the custom of the times) took as his motto, "Wonderful, yet not unfathomable," or, alternatively, "Nothing is the miracle it appears to be". In his pursuit to fulfill this motto, Stevinus made significant contributions to mathematics, engineering, and the earth sciences. As a mathematician, he was the first to advocate the use of tenths towards the establishment of decimals in mathematical calculations. As an engineer, he developed a method of releasing floods via Holland's vast canal system in the event of an invasion. The first achievement mentioned above has great bearing on mathematical calculations in the earth sciences and the second relates to a combination of engineering and the study of the behavior of running water. However, it was his contributions to hydrostatics, astronomy, gravity, and magnetic declination that established his importance to the development of the earth sciences.
Stevinus is often credited as the father of hydrostatics, the science that studies fluids at rest. Prior to his research, many scientists believed that the shape of a container of a liquid influenced the amount of pressure exerted by the liquid on its sides. By this reasoning, a circular lake might experience about the same water pressure all the way around the lake, but the pressure on the walls of a lake with an irregular shape would vary from one area to another. Stevinus mathematically demonstrated that only the area of the liquid's surface and its depth influenced the pressure against the sides. This information is often used by scientists in studying the engineering of wells and the permeability of rocks in the construction of dams as well as the strength of the dam itself.
One of his contributions to astronomy was his early defense of the Copernican model (a Sun centered solar system). Stevinus wrote in support of the heliocentric theory before Italian astronomer Galileo Galilei (1564–1642) came to the same conclusion. However, Stevinus had neither the telescopic evidence of Galileo nor the astronomical data of German astronomer Johannes Kepler (1571–1630) to add significantly to the argument.
Of greater significance to the science of astronomy was a discovery that produced new evidence regarding the relationship between gravity and falling bodies. This evidence would eventually become critical to the understanding of how the Sun holds the planets in their orbits and theories about the entire universe. The discovery was made by dropping two bodies of different weights from a high tower. Stevinus recorded that both objects struck the ground at the same time, despite their weight differences. This information disproved the assumption of Greek philosopher Aristotle (384–322 B.C.) that heavier objects fall faster than lighter objects under all circumstances, an assumption that had stood unchallenged for almost 2,000 years. Most historians argue that Stevinus performed this experiment, or at least played a part in arranging the experiment. Although he preceded Galileo by about three years in recording this discovery, his achievement was later attributed to Galileo. Today, many historians hold that Galileo was not only the first to record the experiment, but that he dropped the weights off the Leaning Tower of Pisa (there is no clear evidence that Galileo carried out such an experiment from the Leaning Tower). Regardless of who recorded the experiment first, it was a giant step away from Aristotelean thinking and eventually led to the Universal Law of Gravitation as outlined by English physicist Isaac Newton (1642–1727).
Stevinus' final contribution involved magnetic declination. Since the time of the Spanish-Italian navigator Christopher Columbus (1451–1506), it was a widely known fact that compasses did not point true north and south. Instead, they pointed toward what is known as the magnetic north and south poles. Because of this anomaly, the reliability of the compass depended on location. The difference between the magnetic poles and true north and south poles is known as the magnetic declination. By calculating and mapping magnetic declination, the navigator's job becomes much easier and more accurate. Realizing this, Stevinus was the first to undertake this task. At the time of his death he had calculated magnetic declination for 43 points on Earth's surface.
Stevinus' dedication to his motto and his work may have kept him from marrying until very late in life, or at least it would seem so. In his sixty-fourth year he finally married and eventually fathered four children before his death in 1620.
Gravitational Constant; Hydrostatic Pressure; Polar Axis and Tilt; Solar System
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