You'll probably need some more info for folks to match up with you. There are a some other websites you might try searching to find more clues. Be open to looking for variations or mispellings of the Hern name. The free ones I'd recommend are:
Family Search (This site has great Boston information, including state census info for the mid/late 1800's.)
https://familysearch.org/
Irish Genealogy
http://churchrecords.irishgenealogy.ie/churchrecords/
Or you can sign up for Ancestry.com which is fee based. You might be able to get free access from your local library.
I did see one family on Family Search in 1855 that could fit. If it's them, search for all the children and the other two Hern's living with them and you are likely to find some more information. You also might want to post the parent and sibling names on some genealogy forums and you might find some cousins who are also researching. Here's the link:
https://familysearch.org/pal:/MM9.1.1/MQWN-ZYP
Good luck!!
Cathy
Chicago, IL