It is thought better that his old housekeeper should give him Lady Dedlock’s letter, the contents of which no one knows or can surmise.
Then I told him all about Mr. Guppy, who I feared might have had his vague surmises when I little understood his meaning, but in whose silence after our last interview I expressed perfect confidence.
There are no more uses of "surmise" in the book.
Show samples from other sources
He has surmised that this is not a friendly visit.
Colleen Hoover -- Slammed
After texting his mom, he started the truck and peeled out of the parking lot, making it back to the ranch a little after four a.m. Seeing the lights on in the main house, he surmised that his mom had either risen early or. more likely, hadn’t gone to bed.