Go to familysearch.org, then 'search for ancestors', then 'census' (to limit your results). Put in Mary Gappins and you will come up with 3, which are on the same census, mother, daughter, and granddaughter. You can see the whole census entry if you click on 'see original image'. It will show you the original image even though it says 'for a fee at ancestry.com', you just can't look at other pages. Anyhow, I do think this is our Mary. I am wondering where the father is. It says Mary, the head of household, is single. Since there is a box for widowed maybe they were divorced? I sort of doubt that. Do you know the parents of Mary?