Re: Leaking Chimney!
You may want to start by checking out this site and watching the videos- http://www.csia.org/
What is probably happening is wind driven rain is blowing in under the cap, a common problem for large chimneys.
With one that old the first thing to do is get it inspected buy a professional who can make recommendations of remedies for any problems before you ever use it. It would be a shame to burn the house down.
Be sure you live your life, because you are a long time dead.-Scottish Proverb