Lips in the Corner, Antique Graphite Sketch

I found this loose along with some other papers accompanying a 19th century note filled with geometric perspective drawings. Of a different ilk than the others, but someone was clearly studying rendering. And while of course I'd love to see the page filled with a hundred sets of lips, there is something rather satisfying about the four mouths clustered at one corner, as if just whispering in one's ear! 

Graphite on wove, with general light wear a bit of scattered soiling/smudges, mostly around the edges Paper 10 3/8" x 7 7/8".