Stone buildings in Brittany

On my third annual visit to Brittany, where I’ve always admired the stonework, I’ve noticed a feature for the first time, though it turns out to be common. The front wall of many houses is finished with a course of dressed stone that curves up and out to form a ledge. This then supports the bottom row of slates, creating an overhang that stops rainwater running down the wall.

This stone is granite and I wonder about its working in the days before powered machinery. How many hours labour did one of those curved stones represent? Or the stones with dressed surfaces in churches? And what tools were tough enough to shape granite? Was iron harder than granite and able to split it, chip it or grind it?

I know nothing about this and will look for a book that tells it all. It’s one aspect of that huge deficiency in all our educations in Britain: there’s no subject about the made world, how humanity has got from piling loose stones and using what lay around to mining, smelting, forging, baking: pottery, metallurgy, chemical technologies with ceramic and metal, etc etc. We get physics and chemistry if we’re lucky but not technology (in its basic sense of how materials are worked to make things).