Also, having been a Lodge Secretary and fielding these kinds of requests, allow me to tell you that your relative's petition is not really going to give you very much information. A lot of people think that they will reap a bunch of genealogical info from a Masonic petition, but it's really not true. Now, a petition will tell you what his address was, and who he worked for, his wife's name (if he was married at the time he petitioned) and basic info like birthdate and birthplace, but most people already have that information. AND that's assuming his petition can be found. Water damage, fire damage, mice or insect damage, and even poor filing procedure all get in the way of discovering an old petition. Be prepared - you just might get disappointed.
As others have already written, being a Lewis (someone with a Masonic ancestor, particularly a father) will not help you become a Mason. And as I've written, a Masonic petition will really not give you much info.