All 11 Uses of

however
in
Treasure Island

None of them dare, however, to deny the merits of the ship.
Chpt 7

however = a word used to connect contrasting ideas as when using though, in spite of that, in contrast, nevertheless, etc.

At last, however, we got alongside, and were met and saluted as we stepped aboard by the mate, Mr. Arrow, a brown old sailor with earrings in his ears and a squint.
Chpt 9

However, we had no luck, for just as Trelawney fired, down he stooped, the ball whistled over him, and it was one of the other four who fell.
Chpt 17

One glance, however, was sufficient; and it was only one glance that I durst take from that unsteady skiff.
Chpt 23 *

At last, however, she fell right into the wind's eye, was taken dead aback, and stood there awhile helpless, with her sails shivering.
Chpt 24

I was prompt with my answer, however, for I saw where my advantage lay and that with a fellow so densely stupid I could easily conceal my suspicions to the end.
Chpt 26

He looked up, however, at my coming, knocked the neck off the bottle like a man who had done the same thing often, and took a good swig, with his favourite toast of "Here's luck!"
Chpt 26

Soon, however, he saw that our party had the start of him; and Ben Gunn, being fleet of foot, had been dispatched in front to do his best alone.
Chpt 33

But the mere fact that he was a man, however wild, had somewhat reassured me, and my fear of Silver began to revive in proportion.†
Chpt 15

Definitions:

(1) (however as in: However, complications may...)
though (or another expression that connects contrasting ideas)

(Based on idea 1 we might not expect idea 2, but this is a way of saying that even though idea 1 exists, we still have idea 2. Synonyms include in spite of that, despite that, nevertheless, nonetheless, on the other hand, in contrastand but.)
(2) (however as in: However much she tried...)
to whatever degree (regardless of how much; or whatever unspecified amount)
(3) (however as in: However you do it, get it done!)
in whatever way
(4) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

Much more rarely (and arguably incorrectly), however can be used to intensify the word how, as when one says "However did you find her?" Grammarians would suggest using two words for that usage: "How ever did you find her?"