"The prophetic destiny of Egypt," from Grip, 1882.

From The Sketch, 1906.

Some sphinxes from Monumentos Antiguos y Modernos by Julio Gailhabaud, 1845.

Here is announced the arrival of an invisible Sphinx propounding unheard of riddles.  From The Widow's Mite by Isaac Kaufman Funk, 1911.

Madame Sphinx, from Mocca, 1936.

It actually takes two sphinxes to turn a crossword puzzle into a riddle.  From Die Bühne, 1925.

The sphinx has had enough with riddles.  From Die Bühne, 1925.   See Presumptive Conundrums: Rhetorical Math Questions + Answers.

A 1910 issue of The Sphinx, the UW Madison campus humor magazine.  See How to Hoodoo Hack a Yearbook.

"Sphinx, Thames Embankment, London."  From 1913.

A Century of Charades by William Bellamy.

"The newest thing in freak photgography: sitters posing for their portraits in sphinxes and a mummy-case, in Egypt.  Our illustration shows visitors to Egypt being photographed in model sphinxes and a mummy-case, in a desire to possess curious—if somewhat gruesome souvenirs of their wanderings by the Nile.  The mummy-case and the sphinxes are of cardboard, and, as may be seen, a hole is left for the face of the sitter."  From The Sketch, 1908.

Here's the earliest "sphinx/thinx" pun we've been able to dig up: ""The mysterious sphinx: who know what he thinx?"  From Grip, 1891.

But there have been some echoes along the way:

The reporters go up to the sphinx

And demand to know just what it thinx

     Of the Philippine Isles;

     But the sphinx only smiles

And replies: "That's a secret, by jinx!"

—The Indianapolis News, 1900

That granite-faced dub called the Sphinx

Has missed many thousands of drinx,

     But equals, perhaps,

     A great many chaps,

In the number of thunks that he thinx!

—William Frederick Kirk, Fleeting Fancies, 1904

Even the enigmatic old sphinx winx as he thinx of the most exhilarating of drinx.

—The Capuchin Annual, 1949

The toffy head waiter with the face of a sphinx

These are a few of my least favorite thinx.

—Bulletin with Newsweek, 1981

The Publisher mysterious enigmatic Sphinx.

The Editor in oracles of rejection thinx.

—Marjorie Bovee, A Soul in Search of Itself, 1999

From The Forester yearbook of Lake Forest University, 1911.  See How to Hoodoo Hack a Yearbook.