keel over

What a tiny little schooner! But is it not bold to spread both sails? And see, now that we have come round to the wind, how the skiff keels over.

We should all go inside before somebody keels over from the heat.

The enemy had planted a piece of ordinance within gun-shot of the fort during the night, and the first thing in the morning they commenced a brisk cannonade, point-blank, against the spot where I was snoring. I turned out pretty smart, and mounted the rampart. The gun was charged again, a fellow stepped forth to touch her off, but before he could apply the match I let him have it, and he keeled over. A second stepped up, snatched the match from the hand of the dying man, but Thimblerig, who had followed me, handed me his rifle, and the next instant the Mexican was stretched on the earth beside the first.