Two hardworking folks (not sure who) digging for the foundation of the domed observatory, later to be known as the Marsh Building at the Leslie V. Powis Hamilton Centre Observatory. The Butler Building is the round, corrugated storage building in the background.

RASC Hamilton Centre 1979_06
Scanned by Colin Haig 2006-03-25
Scanned with Nikon Coolscan V ED.

These slides had a date on the slide mount, 1979 06. Not sure when actually taken or when developed. I think what happened was the slides were taken and developed later. The slides are from the construction of the Hamilton Centre Observatory.

Abbreviations: HBF - written on the slides, I think they are the initials of the photographer. HBF is likely H.B. Fox.