Flying Whalebones

The construction site across the way is using its crane to move roof trusses into place today.
They are huge iron arcs, charcoal ribs gracefully curving from end to end and narrowing to a point decorated with a white flag.
Twisting a little as they are hoisted up and across the building, they give the illusion of a giant Calder mobile.
What a shame when they are welded into place.