By degrees Rip’s awe and apprehension subsided. He even ventured, when no eye was fixed upon him, to taste the beverage, which he found had much of the flavor of excellent Hollands. He was naturally a thirsty soul, and was soon tempted to repeat the draught. One taste provoked another; and he reiterated his visits to the flagon so often that at length his senses were overpowered, his eyes swam in his head, his head gradually declined, and he fell into a deep sleep.
Could you describe in detail what "eyes swam in head" means so that I can picture it?
Is this a commonly used expression? When you want to describe a drunk person?