The Indiana Genealogical Society has published a detailed index to the 1890 soldiers enrollment list for Wells County. For more information (including a sample page), see http://www.indgensoc.org/shop.html

The enrollment lists were the result of an act passed by the Indiana General Assembly. Their purpose was to determine who was eligible for a military pension, by enumerating veterans of all previous wars (or their widows and orphans, if the veteran was deceased) who were living in Indiana counties in 1890. These lists can help determine an ancestor’s military service, and also function as a partial census substitute, since the Indiana portions of both the 1890 census and the 1890 special census of Union veterans and their widows were destroyed.

FYI, the Indiana State Archives (http://www.in.gov/icpr/archives/) has the originals of the enrollment lists—these lists contain even more information than what’s included in the indexes, including details of the injuries and diseases the veteran sustained while in service. The enrollment lists have also been microfilmed and that microfilm is available through the Family History Library, among others.