Do we cite authors or papers when using author/year citations? Numbered citations

In my field, we usually use only numbered citations, e.g.


  As shown in [1], the sky is blue.


This means that we obviously refer to a certain the paper (which can be found under [1] in the reference list). Saying something like 


  As shown by [1], the sky is blue.


doesn't make too much sense, whereas


  As shown by Tyndall [1], the sky is blue.


works. 

Author / year citations

Do we again cite papers when using author / year citations? Is "Tyndall, 1869" our name for a certain paper? Or are we refering to the authors?

In particular, which of this is correct:



  As shown in Tyndall (1869), the sky is blue.


  As shown by Tyndall (1869), the sky is blue.


  As shown by Tyndall (Tyndall, 1869), the sky is blue.


  As shown in (Tyndall, 1869), the sky is blue.





Sorry if this is a duplicate. This question and the answers don't really help.
In general, the final arbiter of this is the style guide the editor is using for the book, journal or collection. If you have no external editor or style sheet then the choice is yours, but the most common usage for inline citations would be not to repeat the name, while leaving the sentence readable with the parenthetical part left out, i.e.


  As shown in Tyndall (1869), the sky is blue.


This is specifically when the name is reused, so it would still be


  As shown in another paper (Tyndall, 1869), the sky is blue.