33
for the speed of light. Rømer’s
compatriot, Bishop Nicolas Steno,
was sceptical of much ancient
wisdom, and developed his own
ideas in both anatomy and geology.
He laid down the principles of
stratigraphy (the study of rock
layers), establishing a new
scientific basis for geology.
Microworlds
Throughout the 17th century,
developments in technology
drove scientific discovery at the
smallest scale. In the early 1600s,
Dutch eyeglasses-makers
developed the first microscopes,
and, later that century, Robert
Hooke built his own and made
beautiful drawings of his findings,
revealing the intricate structure of
tiny bugs such as fleas for the first
time. Dutch fabric-store owner
Antonie van Leeuwenhoek,
perhaps inspired by Hooke’s
drawings, made hundreds of his
own microscopes and found tiny
life forms in places where no one
had thought of looking before, such
as water. Leeuwenhoek had
discovered single-celled life forms
such as protists and bacteria,
which he called “animalcules.”
When he reported his findings to
the British Royal Society, they sent
three priests to certify that he had
really seen such things. Dutch
microscopist Jan Swammerdam
showed that egg, larva, pupa,
and adult are all stages in the
development of an insect, and not
separate animals created by God.
Old ideas dating back to Aristotle
were swept away by these new
discoveries. Meanwhile, English
biologist John Ray compiled anenormous encyclopedia of plants,
which marked the first serious
attempt at systematic classification.Mathematical analysis
Heralding the Enlightenment, these
discoveries laid the groundwork for
the modern scientific disciplines of
a s t ronomy, chem i s t r y, ge ol o g y,
physics, and biology. The century’s
crowning achievement came with
Newton’s treatise Philosophiæ
Naturalis Principia Mathematica,
which laid out his laws of motion
and gravity. Newtonian physics
was to remain the best description
of the physical world for more than
two centuries, and together with
the analytical techniques of
calculus developed independently
by Newton and Gottfried Wilhelm
Leibniz, it would provide a powerful
tool for future scientific study. ■SCIENTIFIC REVOLUTION
1665
1669
1669 1676 1686
1670 S 1678 1687
In Micrographia,
Robert Hooke
introduces the world
to the anatomy of
fleas, bees, and cork.Nicolas Steno writes
about solids (fossils and
crystals) contained
within solids.Jan Swammerdam
describes how
insects develop in
stages in Historia
Insectorum Generalis.Ole Rømer uses the
moons of Jupiter to
show that light has
a finite speed.John Ray publishes
Historia Plantarum, an
encyclopedia of the
plant kingdom.Antonie van
Leeuwenhoek observes
single-celled
organisms, sperm, and
even bacteria with
simple microscopes.Christiaan Huygens first
announces his wave
theory of light, which
will later contrast with
Isaac Newton’s idea of
light as corpuscular.Isaac Newton outlines
his laws of motion
in Philosophiae
Naturalis Principia
Mathematica.