You were right to check the 1911 census. Did you also check the 1901 census records here?: http://www.census.nationalarchives.ie/search/ Names in instutions are usually in initial form (such as Mary Kelly would be "MK").
You might fid this link of interest: http://www.workhouses.org.uk/DublinNorth/
The National Archives of Ireland has 1840-1938 Admissions and Discharge registers for Dublin city workhouses (North and South Unions).
Civil registration records are available from the General Register Office (GRO). These start from 1864 however. You can access the website here: http://www.groireland.ie/research.htm
You could also find out the military background of John Edwin Barnes. The UK National Archives is the best place to check for this: http://www.nationalarchives.gov.uk/
You could also try checking the land records called the Tithe Applotment Books (1823-38) or the later Griffith's Valuation (1848-64). Griffith's is freely available here: www.askaboutireland.com or here: www.failteromhat.com Failte Romhat has lots of other useful links you could try looking at.
Please make sure you link anyone else in your family who is interested in their Irish heritage to our site - and indeed anyone else you know of Irish heritage.
Genealogist (Ireland XO)