There is the following passage in a famous novel of Edgar Allan Poe, “The Golden Bug” written in 1843.
“Having carefully taken the bearing of the tree, I turned homewards. The instant that I left ‘the devil’s seat,’ however the circular rift vanished: nor could I get a glimpse of it afterwards, turn as I would.”
How should I interpret the phrase, “turn as I would.”? Is this usage of 'as' very common? Does it mean '(though) Legrand, the teller looked back again and again the bearing of the circular rift where a death's-head is placed'?