During Dorcas’ lifetime, the world made the transition from a largely religious-centered society to one focused around science and reason. Many great philosophers and scientists appeared during this time, and their impact is unprecedented in world history.

When Dorcas was about five years old, in 1650, Rene Descartes died. He is best known for his famous phrase, “Cogito, ergo sum” (I think, therefore I am). In science, his most important contribution was his discovery of the law of reflection, which stated that the angle of incidence is equal to the angle of reflection. His works also laid the groundwork for the undulatory theory of light. In mathematics, he was the first individual to express powers and to classify graphs based on the equations that produce them. He formulated Descartes’ rule of signs for finding negative and positive square roots for an equation.

In 1660, ten years later, the English physicist and chemist Robert Boyle published his work, The Spring of Air, in which he brought together his observations on gas over the past years and formulated Boyle’s Law. This law states that a gas’s volume is inversely proportional to the pressure exerted on it. Boyle was also the first physicist to distinguish between mixtures and compounds. In 1663, he founded the Royal Society of London for Improving Natural Knowledge. He was elected its first president, but declined to assume the position.

Thirteen years later, when Dorcas was 28, Christiaan Huygens published Horologium Oscillatorium, in which he determined the relationship between pendulum length and oscillation time. He also invented the first pendulum clock, which was a great improvement in keeping track of time. Huygens was furthermore noted for developing theories on centrifugal forces, some of which would lay the foundation for Newton’s theory of gravity.

Olaus Roemer, in 1676, attempted the first measurement of the speed of light, when Dorcas was thirty-one. He noticed a variation in the timing of the eclipse of Jupiter’s moons. He concluded that this was due to the changing distance between the Earth and Jupiter, and consequently the amount of time it would take for light to travel that distance. His conclusion was verified in the 19^th century by Armand Fizeau and Albert Michelson and his colleagues.

       

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