"A new system of sword exercise for infantry" by Richard Francis Burton, 1876.

"We believe that the earth is round," from First Lessons in English by Alfred Hix Welsh, 1889.

Air, water, earth, and the sun.  From the Annual Report of the Board of Regents of the Smithsonian Institution, 1846.

From Bericht Über die Senckenbergische Naturforschende Gesellschaft in Frankfurt am Main, 1894.

From Class-Book of Botany by Alphonso Wood, 1881.

From Cl. Galeni Pergameni Ars Medica, Quae et Ars Parva Dicitur, 1548.

Here's how to find an inverted pentagram's anus.  From The Biological Bulletin, 1922.

Note how "Hard Sky" and "Watery Sun" are two of the conditions in this weather chart from A Directory for the North Atlantic Ocean, Comprising Instructions General and Particular for its Navigation, 1918.

Geneticists have found DNA markers associated with mathematical ability.  And here's a precursor to that: Sudoku in embryo, from Die Stoffliche Grundlage der Vererbung, 1921.

You've heard of The Importance of Being Earnest.  Here's how Ernest came to be drawn more fully than some other characters.  From Biology and Man by Benjamin Gruenberg, 1944.

Above and below, from the Arthur and Fritz Kahn Collection, courtesy of the Leo Baeck Institute Archives.

From the Annual Report of the American Institute of the City of New York, 1862.

From the Smithsonian Institution's Bureau of American Ethnology's Bulletin 64, 1918.

Here's the so-called turkey dance of the Utes.  Dancers sit along the circle (A).  Drummers with their drums are seated at B.  The leader begins the dance at C and traces the arrowed path, followed by the dancees.  "The erratic motion is continued indefinitely."  From the Smithsonian Institution's Bureau of American Ethnology's Bulletin 75, 1922.

"'Too low they build, who build beneath the stars.' —Young.  From A Practical Grammar by Stephen Watkins Clark, 1847.

This is the symbol left in the crib after the Lindbergh baby was famously taken away.  "There has been no genuinely convincing analytic work done on [this symbol] with respect to the Lindberg story" (Jerry Kroth, The Lindbergh Kidnapping, 2011).  [Note that the three black rectangles are actually holes that were punched in the paper and are not technically part of the design.]  The shaded object in the center is, of course, the "black egg" of alchemy, symbolizing the nigredo (a stage of putrefaction; the final step toward the "philosopher's stone" of enlightenment) and expressing "the precarious balance of the hermaphrodite, exalted by a [threatened] equilibrium" (Johannes Fabricius, Alchemy: The Medieval Alchemists and Their Royal Art, 1994).