Here's something I found:
http://www.library.dal.ca/duasc/dcmackay/
There are also some surprising sketches of various towns around the Maritimes.
Some samples:
British Merchants' Coffee House, Water Street
I think this is around Duke and Lower Water (1936)
George Street at Argyle, 1927
Hollis Street South of Salter, 1929
Sackville, Queen, and Dresden Row (that house is still there)
Untitled, 1928 (Grand Parade looking up George Street)
Plant Wharf, 1927
Wharf scene, South Ordnance Yard, 1929