changing the name of a variable by another variable.

I really am having a difficult day. I want to do an incrementing while loop that will echo out the values of $variable1 , $variable2, $variable3 which exist previously. so how do I get the incrementing number onto the word variable? to make a new variable that matches thename of the existing ones.. I tried echo $variable$increment ; but $variable doesn't exist alone so all I get is $increment. I'm not sure what I should be looking for in the manual - google's not much help either. anyone give me a clue? TIA Tony