What's exactly meant here by "smiled deprecatingly"?

Question

In "The Blue Scarab" in Dr. Thorndyke's Case-Book by R. Austin Freeman, Mr. Blowgrave, whose deed-box was stolen, was talking to Dr. Thorndyke:

He took from his pocket and handed to Thorndyke an ordinary envelope addressed in typewritten characters, and sealed with a large, elliptical seal, the face of which was covered with minute hieroglyphics.

"This," said Thorndyke, "I take to be an impression of the scarab; and an excellent impression it is." "Yes," replied Mr. Blowgrave, "I have no doubt that it is the scarab. It is about the same size."

Thorndyke looked quickly at our client with an expression of surprise. "But," he asked, "don't you recognise the hieroglyphics on it?"

Mr. Blowgrave smiled deprecatingly. "The fact is," said he, "I don't know anything about hieroglyphics, but I should say, as far as I can judge, these look the same. What do you think, Nellie?"

Does it mean "in embarrassed way" or "in a way that made him look fool"?

Answer 1

You've accepted the answer, and it may be right of course. But in the context of the quoted passage it seems to me that quite the opposite is intended.

When we are self-deprecating we are modest or self-critical. Mr. Blowgrave smiles self-deprecatingly. He is a little embarrassed to admit he knows nothing about hieroglyphs.

A little over a century ago, when R. Austin Freeman was writing, deprecatingly was used precisely the way we use *self-deprecatingly" today.

"But I am so unworthy," she said deprecatingly

-The Pacific Monthly, 1902

She came down to tea all white muslin and lace and pink ribbons. "It's Yolande's fault," she said deprecatingly. "I hate being smart myself. It's so unsuitable to our position. Don't look at me like that!"

-Harper's Bazaar - Volume 36, 1902

"Nothing — Never mind me, —" she said deprecatingly.

-Say and Seal, 1895.

"I'm afraid it isn't exactly 'delicate,'" she said deprecatingly. "Jenny says it is in a ridiculously sentimental fashion," she said carelessly.

-All the Year Round, Volume 74, 1894

It is a complicated story, but while deprecate has retained its dictionary meaning, self-deprecating has adopted the meaning of the word self-depreciatory, meaning 'belittling or disparaging'.

Bryan Gardiner, in his Modern American Usage, bewails the withdrawal of the word depreciate into financial contexts. Undoubtedly we should be saying self-depreciatingly, but we don't. Yet to disapprove of ourselves earnestly is, as he points out, virtually impossible.