Hi RK,
This is really interesting and not off-base!! Please read my response last evening to Jacquie where I referenced what I had found on the Rockland site. I really believe there is a connection here. I haven't had a chance yet to look at the family search site but I will.
From what I have read on this family, Robert Addison Mather seemed to have traveled at times pertaining to the family's lumber business and Eau Claire seems to have been one of these places. I checked out Eau Claire on Google and found it was apparently known as "Sawdust City"; there were numerous sawmills along the Chippewa River, the Eau Claire River and Half Moon Lake. Beginning in the 1830s, Eau Claire had the geography for the beginnings of a large production in the lumber industry. There seems to be a huge connection there with the Mathers and the Camerons....even a variation of the name, McCaul is mentioned.
Robert A Mather was not the only brother who traveled or married in the U.S., for that matter. The last born son of John and Jane Mather and brother of Robert A and David Low, was Allan Gilmour Mather. His middle name came from the well-known Gilmour family of Gatineau who owned sawmills there and where John Mather came to work when he emigrated from Scotland in 1857. I accidently found Allan's marriage year (1897 - year only)) and the name of his wife (Grace Leonard) when I was searching through old Ottawa newspapers and found an obit for her in 1947. They emigrated in either 1911 or 1912 from the U.S. It could have been Minnesota...I seem to remember the location from when I started researching this family years ago. Can't find my reference to this, however, there were at least 36 flour and other grain mills in Minnesota, so this could be right. Grace Leonard was born in England and moved to the U.S. when she was five yrs. old. Allan Gilmour was the engineer of the family and managed his father's flour mill business while Robert A and David Low managed the lumber end of it.
Many thanks for this information, RK
Dorothy
Possible marriage for Robert A. Mather and Maud Cameron on 24 April 1878 in Eau Claire Wisconsin!! Have a look at the familysearch site. This may be totally off base, but his parents are John and Jane Mather. Hers are A. Cameron and Margaret ?
RK 
http://www.rootschat.com/links/0cdg/
Lots of your Mather relatives are on this site.
