I fancy

"Well, well, — I wrote what pleased myself; and, — another object I have, which I did not mention: with scarce a book to read, if one did not write,
I fancy the beef and pork and beans would in time form a coating round his brain; — turn it all perhaps to thick and solid skull! How is it with you, Frank? Does yours retain a slight softness?"  

"Scenes Beyond the Western Border," August 1853; and (with "Frank" revised to "my Friend") Scenes and Adventures in the Army

  "I fancy that this moment Shakspeare in heaven ranks with Gabriel, Raphael, and Michael." (Letter to Evert Duyckinck, February 1849)

"By the way, I have recently read his 'Twice Told Tales' (I hadn't read but a few of them before). I think they far exceed the 'Mosses.' They are,
I fancy, an earlier vintage from his vine. Some of those sketches are wonderfully subtle. Their deeper meanings are worthy of a Brahmin.  Still there is something lacking—a good deal lacking—to the plump sphericity of the man. What is that? — He does'nt patronise the butcher—he needs roast-beef, done rare."  (Letter to Evert Duyckinck, February 1851)

“There are times when I fancy myself a lunatic,” resumed Babbalanja.

“Ah, now he’s beginning to talk sense,” whispered Mohi.  (Mardi)