Recent New Scientist mentioned this word, so I searched for some information about them.
I do not claim to understand them at all well, but the closest I can come to describing them
is to say they are a sort of mechanical analog computer, giving dates and times for tides,
sunrise, sunset,etc.,etc.
"The Oxford English Dictionary, 2nd. ed. Volvelle, also voluell(e): An old device consisting of one or
more movable circles surrounded by other graduated or figured circles, servicing to ascertain the rising
and setting of the sun and moon, the state of the tides, etc. "
"Volvelles are believed to be the primal species of interactive book. Astronomers used them to predict the
position of the moon, while mystics used them to predict the future. One of the oldest known movable books is a
13th-century volvelle by a Catalan mystic, the exhibit notes, though it is not on display. Earlier examples would
have been a welcome addition to this charming exhibit, which features more than 300 books from the 16th to
20th centuries drawn mainly from the collection of pop-up producer Waldo A. Hunt, with some volumes on loan
from the library and UCLA. "
'Petrus Apainus (the royal astronomer to Charles V, emperor of the Holy
Roman Empire, 1519-56) published "Astronomicum Caesareum" at his own
private press in Ingoldstadt, Germany, in 1540. Some of the 21 large,
complex volvelles in the folio contained as many as six rotatable dials that
showed central, eccentric and epicyclic motion to harmonize with the
Ptolemaic theory of stellar movements. In payment for this masterpiece,
Charles V gave Apianus the sum of 3,000 florins and granted him a patent of
nobility in 1541."
OP
