How Invention Begins ch. 4
The steam engine:
"Science owes more to the steam engine than the steam engine owes to science." L. J. Henderson (1917)
The laws of thermodynamicswere discovered by scientists trying to understand how steam engines worked. But Leinhard gives a closer look and sees a back and forth between science and technology
If they didn't have the laws of thermodynamics, what kind of knowledge was used to invent the steam engine?
Ancient World
Early Modern era:
"Science owes more to the steam engine than the steam engine owes to science." L. J. Henderson (1917)
The laws of thermodynamicswere discovered by scientists trying to understand how steam engines worked. But Leinhard gives a closer look and sees a back and forth between science and technology
If they didn't have the laws of thermodynamics, what kind of knowledge was used to invent the steam engine?
Ancient World
- In ancient Greek times (Hellenic)--mathematics seemed
powerful (Pythagoras)
- Aristotle (384-322 BC) popularized the idea that there were four elements--earth, air, fire, and water
- Aristotle wrote an encyclopedia that was seen as the basis of all knowledge for nearly 1500 years
- Aristotle was particularly influential, and he said "Nature
abhors a vacuum"--meaning it was not
possible to create one--discouraged steam engines
- after Alexander the Great (Hellenistic period) technology became somewhat more respected
- Ktesibios invented machines using compressed air
- Philon
wrote a book about devices powered by air pressure: Pneumatics
- Hero (or Heron) of Alexandria built a steam engine as a toy--see diagram
- Hero's engine was not put to practical use
- why not?
- hard to get useful work from this design
- not much interest in labor-saving technology--had slaves
to do the work
- attitude that practical work was beneath the dignity of
educated people
- Maria the
Jewess (audio)
developed methods of distillation
Early Modern era:
- Scientific Revolution
- overthrowing Artistotle's ideas by the use of experiments
- Copernicus used the old methods (1543)
- Copernicus said the earth went around the sun--that made it easier to calculate the calendar and the positions of the planets--but the physics of the time couldn't explain how that could happen
- Galileo not only found observational evidence for Copernicus's ideas, he also started the process of inventing the necessary theories of physics so that Copernicus's theory was possible
- Kepler made more careful calculations and showed that the planets move in elipses, finally throwing out Aristotle's theory that heavenly bodies must naturally move in perfect circles (because the heavens are perfect and the circle is perfect)
- all of this set up Isaac Newton, who invented the calculus
in order to be able to show that his theory of gravitation explained
the motion of the planets (1690)
- Pierre Gassendi understood air pressure as the motion of particles in a gas
- Magiotti worked with barometers (invented by Torricelli)--measure air pressure
- barometer:
fill a tube completely with mercury, and turn it upside down into a
bowl of mercury. The mercury won't all spill out, since air can't
get into the tube, but if you have a very long tube the column of
mercury will only be 30 inches high. This measures the pressure
of the atmosphere.
- Magni independently invented the barometer and argued that it had a vacuum at the top
- scientists were interested in proving that Aristotle was
wrong, that it was possible to create a vacuum
- Magnenus
began to develop a theory of atoms
- Otto von
Guericke showed the power of air pressure--watch the video
of a recreation--when he pumped air out of a metal sphere to create
a vacuum the air pressure on the outside of the sphere compared to the
vacuum inside was so great that teams of horses couldn't pull the two
halves of the sphere apart