Is there a word for the act of dimming an oil lamp?

A friend of mine had this request:

Alright so I was sitting at this table with a kerosene lamp, and it was a little too bright. Watch out! So I turned a little knobbly thing to lower the flame, and then had the vaguest recollection that there was some verb for this precise action, the dimming of an oil lamp, but a week of pondering and now some searches for "list of lamp actions" have not flushed out any foxes. Can anyone toss me some helps on this one? I think it may be an archaic word that one would find in Charlotte Bronte or Laura Ingalls Wilder, also maybe the kind of word that the Decemberists or Joanna Newsom would bandy about to show they mean nineteenth-century business.

I briefly checked the OED online and some other sources (well, Google) but didn't find anything sufficiently specific. Does anyone know if this word actually exists?

Trim

Here's the ngram graph for "trim your lamps," "trim the lamps," "trim your lamp," and "trim the lamp."

There's also "bedim":

bedim verb \bi-ˈdim, bē-\ 1. to make less bright

First known use: 1565

Other than that, just "lower" or "dim". You can also "trim" an oil lamp (or more accurately, its wick).

Of course, there's "extinguish" or "douse", but those aren't the same.

Not very helpful, I'm afraid.

The Oxford Compact Thesaurus suggests:

dim verb 1 the lights were dimmed: turn down, lower, dip, soften, subdue, mute.

Of those, 'turn down' is the most likely synonym, though 'dip' might also work.

Does "lower" not work here?

"Let me lower the lights." "He lowered the light."

With an oil lamp, it would have been additionally relevant, since the act of turning down the dial on a kerosene lamp actually lowers the wick into the base of the lamp, which lowers the flame...