Meaning of the word "butterglance" to describe a woman's way of looking at someone

I found this word in a rhyme inscribed on the fly leaf of a book of American poetry and dated 1878. You can see the poem listed in Edith Wharton's Library: a catalogue, which was written by George Ransden and published by Stone Through in 1999:

pc One poem marked in the Contents list and that one and another in the text, possibly by the writer of the rhyme on the flyleaf:

In this book dear girl/ Find a truthful utterance /

For the thoughts that whirl / Oft expressed in butterglance"

[Signed] WBB³

I can't find anything in the O.E.D., and Google Books does not reveal too much either, aside from the aforementioned source and a couple of potential mentions which can't be previewed.

You can also find what looks like an original handwritten version of the poem which can be seen on the Edith Wharton's library website, hosted by Sheila Liming, Assistant Professor of English in the University of North Dakota. It is handwritten on a copy of The Poems of Thomas Bailey Aldrich, published by Boston Ticknor and Fields in 1865. Above it is inscribed "Edith Jones - Oct. 11th 1878", which may be an indicator of who owned that copy of the book, and when she first got it.

Solution 1:

As mentioned by @SGR and @Sven Yargs, this seems more than likely to be a contraction of 'but a glance' and possibly a play on words.

There is a recent slang term of (probably) similar provenance: butterface, defined in Jonathon Green, Chambers Dictionary of Slang as follows: "butterface n. {i.e. but her face} {2000s} (US black) a female whose body is very attractive, but who has an unattractive face." It seems likely that butterglance is a contraction of "but her glance." -Sven Yargs