Heron of Alexandria fashioned the fi rst known “steam engine,” though he only
used it to power toys and amuse visitors. Encyclopædia Britannica, Inc.
7 Heron of Alexandria 7a hollow sphere mounted so that it could turn on a pair of
hollow tubes that provided steam to the sphere from a
cauldron. The steam escaped from the sphere from one or
more bent tubes projecting from its equator, causing the
sphere to revolve. The aeolipile is the fi rst known device
to transform steam into rotary motion. Like many other
machines of the time that demonstrated basic mechanical
principles, it was simply regarded as a curiosity or a toy
and was not used for any practical purpose.
The Belopoeica (“Engines of War”) purports to be based
on a work by Ctesibius of Alexandria (fl. c. 270 BCE ).
Heron’s Mechanica , in three books, survives only in an
Arabic translation, somewhat altered. This work is cited