Cornerstone of the Theolgical Hall at Queen's University, Kingston, Ontario

Something different - a modern stone with a Latin inscription

HVNC LAPIDEM
VIR NOBILISSIMVS
LORNAE MARCHIO PRAESES CANADAE
POSVIT
A.D III KAL. JVN. MDCCCLXXIX

This Stone
the most noble man
the Marquis of Lorna, President of Canada
placed
on the third day before the Kalends of June (May 30), 1879

Several curious things:  I can't find any reference to either:  Lorna, a Marquis of Lorna, or a Praeses Canadae.  At first I thought "Lornae Marchio" was a name, but could not find any reference to anything remotely like it.  I also thought there wasn't a President of Canada, unless "Praeses" refers to something more like "Governor General"?

Here's a picture from the other side of the doorway that gives some clues:

HUNC LAPIDEM
ILLVSTRISSIMA PRINCIPISSA LOVISA
LORNAE MARCHESSA
POSVIT
A.D III KAL. JVN. MDCCCLXXIX

This stone
the most illustrious Princess Louisa
Marquessa of Lorna
placed
on the third day before the Kalends of June (May 30), 1879

From this I deduced that "Marchio" must be the masculine form of "Marchessa", and the Princess Louise is probably Louise, Princess Royal (1867-1931), the 3rd child and eldest daughter of King Edward VII, wife of Alexander Duff, the 6th Earl of Fife.

I'm guessing that "Lorna" is Latin for some part of Scotland, but I'm still not sure what "Praeses Canadae" might signify.