JF Ptak Science Books LLC Post 508
"And even though I'm sitting waiting for Mars
I don't believe there's any future in cause
Hole in the sky, gate way to heaven
Window in time, through it I fly..."
Black Sabbath, "Hole in the Sky", 1975
Well, there were many liberties taken with this title, though on the face of it, the title is correct (sort of). This image comes from a relatively obscure (or at least quite rare) copy of Joachim Dalance's work Traite de l'Aiman, divise en deux parties, la premiere continent les Experiences et la seconde les raisons que l'on en peut rendre... which was printed by Henry Weinstein in Amsterdam in 1687 (just across the waters in London Isaac Newton's fantabulous Prinmcipa Mathemtica was being printed in the same year). This important work on magnetism featured a number of good and useful observations on magnetism, interspersed with some semi-useless bits: the magnetically floated coffin of Mohamets is mentioned and disproved, the origin of magnetism is asserted by hypothesis and is not pretty, along with some "fanciful conception(s) of the magnet's potential"*; on the other hand, there is a mention of the invention of the compass, the real use of magnets, a mention of declination, and the orientation of a compass needle in a magnetic field is shown. All pretty good stuff, considering the time. (The magnum opus on the magnet was published in 1600m by William Gilbert and was called De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure (On the Magnet and Magnetic Bodies, and on the Great Magnet the Earth), though folks have been writing on magnetism since Aristotle and Thales)
M. Hofer, the author of the quote above, mentions that the pamphlet's images "are particularly good scientific illustrations", though doesn't mention this, figure 2, as being anything significant. Trying to dissect the phenomenal imagery, which purports to depict the origins of the sources of magnetism, we see something like a "magnetic cloud" in the sky, about to be pricked by a needle held by the primum mobile. That, or it is a missing piece of sky, a gapping hole, though not in the sense of what we're getting now in the ozone layer, or in the fantastic billion-light-year wide swath of nothingness in the foamy universe. Perhaps it is more like the Black Sabbath lyrics after all, a hole in the sky, pricked by the creator, to loosen the fabric of magnetism and getting a glimpse of heaven. Or something.
[I should point out that Dalance was an out-and-about guy, with high-level correspondence, and who seemed to be at the right places at the right time. Among many contributions to the sciences, Dalance--who was a friend of Henry Oldenbourg, helped introduce Huygens to the Royal Society as well as to the French Academy of Sciences, acting as an intermediary for the most part. He seems to be an interesting guy.]
*--Ph. Hofer, Baroque Book Illustration, page 42