Archimedes and the Golden Crown

 

By Eoin Bennett

 

In science, it is common practice for scientists to continually question what is thought to be absolute truth.  Scientists will continually verify or disprove the various hypotheses and theories in the hopes of new discoveries.  In essence science hopes to prevent humanity from blindly accepting opinions as the gospel truth in the absence of supporting scientific evidence.  When reading a story it is easy for one to become enamoured with the story and accept it as what really happened.  The story of Archimedes and the Golden Crown is one such story.

Archimedes was an advisor to Hiero II, King of Sicily.  King Hiero worshipped Greek Gods and wished to create a golden crown to be placed on the head of one of his Greek God statues.  He entrusted his best craftsman with a certain amount of gold from which to craft the new crown.  Upon completion, the crown was truly exquisite.  However, King Hiero had a sneaking suspicion that something was not right.  The crown weighed the correct amount but that did not guarantee it was pure gold.  He suspected the craftsman of substituting silver for gold in the middle of the crown.  Unfortunately, King Hiero had no evidence to support his suspicions.  The case was then turned over to Archimedes.  As Archimedes pondered the matter he went down into the baths to bathe.  As he immersed himself in the water he noticed that the amount of water that flowed outside the bath appeared to be equal to the part of his body that was immersed in the water.  Archimedes knew that he had discovered a way to see if the crown was made of pure gold.  The crown should not only weigh the same amount but when immersed in water should displace the same volume of water as an equal amount of gold.  He put a weight of gold equal to that of the crown into a basin and filled it to the top with water.  Next, he would remove the weight of gold and replace it with the crown.  If the water flowed over then the crown must be made up of gold plus some other substance.  He immediately put his hypothesis to the test.  When he put the crown into the water the water did indeed flow over the basin and the King had his evidence to prove that the craftsman had been fraudulent.

This story provides an explanation of how Archimedes’ Principle of buoyancy came to be.  That principle states that the force of buoyancy is equal to the weight of the fluid displaced by the object.  The story tells us one way this may have happened.  The following explanation is somewhat different.

An alternate explanation for how Archimedes detected the fraudulent crown is as follows.  Archimedes used a balance scale.  On one end he put the crown and on the other end he balanced the scale with a piece of pure gold.  He then immersed both objects attached to the scale into water.  If the scale remained balanced, the crown and the gold have the same density and the crown is made of pure gold.  However, if the scale tilts in the direction of the gold, then the gold must have a greater density than the crown.  The crown must therefore be made of gold and some other lighter substance. (http://www.mcs.drexel.edu/~crorres/Archimedes/Crown/CrownIntro.html).

 

Questions for Discussion

 

  1. Is it possible to have 2 explanations for how Archimedes developed his principle?
  2. Which explanation makes more sense scientifically? Justify your answer.
  3. Should a budding young scientist simply accept what he/she reads as the gospel truth or should that young scientist ask his/her own questions and formulate their own answers?
  4. What should you do before deciding which explanation is correct?

 

References

Bendick, Jeanne. Archimedes and the Door of Science.  Bethlehem Books/Ignatius Press, 1995.

Lexau, J.M. Archimedes Takes a Bath.  Thomas Y. Crowell Company, 1969.

Websites

http://www.mcs.drexel.edu/~crorres/Archimedes/contents.html

http://hyperphysics.phy-astr.gsu.edu/hbase/pbuoy.html