The Rochester Historical Society's phone number is
(603) 330-3099 and it is my understanding that they meet the 2nd Thursday of every month at 7:00 pm .
But you might like to call to make sure.
Are you interested in Rochester's history or genealogy?
The historical society offers a book named "The History of Rochester New Hampshire 1722-1890" which has a wealth of history and birthdates plus marriages during those years.
I bought the book this summer and I love it.If you don't want to pay for it the Rochester Library has a copy upstairs in the research department.