The concept of storing energy for later use has been around for
centuries.  The practical applications of stored energy range from
simple machines to complex high-tech ones.  Mechanical music
instruments such as small music boxes, and some larger instruments
as well, normally include a device such as weights or a spring which
stores the energy to make the instrument play.  Although the machine is
more complicated, in its basic form the energy is stored up by someone
turning a crank which winds up the weights or the winds spring motor
tighter and tighter.  When the stored energy is finally released, the
weights slowly fall or the spring slowly unwinds, causing the music box
to play.

In many respects, this process is similar to a catapult.  Both machines
use stored energy to produce action.  With the catapult, a flexible
(spring) lever attached to a rope and spool mechanism has increasing
backward pressure applied to it by winding the rope around a spool or
cylinder ever tighter, storing up energy.  While a music box's energy
is released slowly to play music, the catapult's energy is released
quickly with the severing of the rope to obtain maximum speed and
distance.

Are catapults and music boxes the only mechanisms that release stored
energy?  Certainly not.  The idea of using stored energy is an old one
which has appeared in various forms over the centuries in both fast-
and slow-release methods.

Examples of fast-release mechanisms include such low-tech items as the
bow and arrow and the slingshot, and high-tech equipment such as an
aircraft launcher on a carrier.  As with the catapult, these fast-release
mechanisms are employed to launch a projectile.

Human stored energy is used by many athletes to launch projectiles such
as a baseball, discus, shot-put or javelin.  A spin, kick, or run helps
the athlete produce maximum energy for launching.  Biomechanics, or
computer analysis of human movement, helps an athlete study his or her
body movements and make adjustments to improve performance.

While fast-release of stored energy is often used for propelling an
object with speed and power, slow-release of stored energy has other
uses besides the music box.  Pioneers created a lathe by tying a cord
to the top of a sapling tree and then winding the cord around a large
spool, causing the tree to bend considerably.  Then as the cord was
slowly released, the tree began returning to its natural position,
causing the cord to unwind on its spool.  In this way, early settlers
were able to create a simple lathe using the laws of nature and
physics.

A modern version of this principle has been applied in recent years.
Wind-up and hand-crank technology has been used as a power source for
radios and flashlights.  These wind-up machines are particularly useful
in remote areas where batteries or an electrical power source are
difficult to come by.  The wind-up power source is a renewable type of
energy, making it cost-efficient.

Stored energy and spring-wound mechanisms are just some of the many
concepts and inventions that have been employed to create mechanical
music machines.  By contemplating these concepts, we can better
understand how these machines operate.

Joyce Brite
Player Piano and Mechanical Music Exchange
http://mmd.foxtail.com/Exchange/