About 1650, steel was hardened by repeated quenchings and
temperings when the steel had reached certain colors. Brass was
made from copper and zinc alloyed together.
There were power-driven rolls for the coinage from 1657. Strips of
silver were passed between engraved rolls. Then coins were punched
out and their edges serrated.
In the 1650s, Huygens invented the pendulum clock, which increased
the accuracy of time-keeping tenfold.
There was a thermometer which used liquid such as water or alcohol
in a glass tube instead of air.
Dutchman Stevinus showed that the pressure at the bottom of a
column of liquid is proportional to the height of the column, and
not to its bulk, about 1634. He also studied oblique forces, and
the balancing of such that could bring about "stable equilibrium".
At a time when mathematics was only a business of traders,
merchants, seamen, carpenters, and surveyors, mathematician John
Wallis, the son of a minister, studied sections of cones as curves
of the second algebraic degree. He worked with negative and
fractional exponents. Around 1655 he invented the infinite
arithmetic and introduced the symbol for infinity. He determined
that the area under any curve defined by the equation y = (x to
the nth power), was x to the (n+1)th power divided by n+1. ,
Blaise Pascal, a French mathematician, physicist, and religious
philosopher, constructed a calculator in 1644 to assist his
father, who was involved in local administration, in tax
computations.
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