Hero (as he is better known) was quite the genius, basically the Leonardo of his day, without the painting. Mathematician, engineer, author. Some of his books have come down to us along wiht lots of fragments of more. He seems to have worked at the edge of what was possible, which is one reason his steam engine was never more than a toy; the materials of the day just weren't up to doing real work.

I wonder, though, how many of the engines he described were ever more than theoretical. This may be like claiming armies in Leonardo's day had tanks and flamethrowers. As for duping people in the temples, I have my doubts. If the devices were ever built, there is no reason that people would not have understood them as allegories of the god working his stuff. They were no doubt impressive, but we're talking about Alexandria here, the home of the best thinkers of the day.

Wikipedia has a decent short article with some good links.