From: Patent Tactics, George Brock-Nannestad

> After many seasons, the lead or wood weakens, and the glass
> begins to bulge.
> Lance Watsky

------ the lead will not weaken, because it has a self-annealing property
that is very active at the very low rate of change. Glass will not bulge - it
breaks. That may be seen in houses that have a sinking corner (eventually
making the windows into parallelograms). The panes do not follow the change
of shape.

Kind regards,