Herman Melville’s assertion on the reverse magnetization of a compass is entirely plausible.
Lightning involves very high currents with high associated magnetic fields.
They remagnetize exposed outcrops of high-coercivity, high resistance to the effect of an applied magnetic field, rocks with ease. Currents exceeding 10,000 amperes have been deduced from rock magnetizations.
The associated magnetic fields could easily demagnetize or reversely magnetize a compass needle.
A moving electrical field will induce a magnetic field, and an electrical discharge such as lightning can easily cause a compass needle to lose or reverse its magnetization.
What the questioner failed to mention is that Captain Ahab fashioned a new compass by striking a sailmaker’s needle and thereby magnetizing it.
This phenomenon is possible and has happened. It has been demonstrated more than once by accidentally dropping a pair of expensive tweezers used for handling metallurgical samples. The fall was sufficient to magnetize the tweezers.
Ferromagnetic materials are composed of microscopic magnetic domains, which may be oriented in random directions producing a demagnetized state.
By aligning the domains in more or less the same direction, the material becomes magnetized.
In some cases, a sharp blow will impart enough energy to make this happen.
Related Posts
-
Where does the term “devil’s darning needle” come from and What does devil’s-darning-needle mean?
Devil's-darning-needle is the common name in the United States of the dragonfly (which see). We abridge it sometimes to darning-needle, and, a hundred years ago, Thoreau and others spoke of the insect as…
-
What’s the difference between thunderstorm warnings and thunderstorm watches?
The difference between thunderstorm warnings and thunderstorm watches is the same as a tornado watch and warning: A thunderstorm watch means that all the ingredients are in place to possibly create a severe…
-
Which Way Would a Compass Point In Space and How Far Above the Earth Would a Compass Stop Pointing North?
The magnetic field of the Earth looks like a dipole, the shape formed by iron filings around a bar magnet, although the Earth's is rotated about the field's axis to form a three-dimensional…
-
How did Dick Fosbury change the techniques of high jumping with the the Fosbury Flop?
In Mexico's Estadio Olimpico, a crowd of 80,000 gasped as high jumper Dick Fosbury flew over the bar at seven feet, four and a half inches to win a gold medal in the…
-
Where does the expression “Tom, Dick, and Harry” come from and What does it mean?
The group of names "Tom, Dick, and Harry" signifying any indiscriminate collection of masculine representatives of hoi polloi was a more or less haphazard choice. It probably started with names common in the…
-
Where does the expression “as tight as Dick’s hatband” come from and What does it mean?
The expression "as tight as Dick's hatband" means: Absurdly queer, or, as the case may be, inordinately tight. The "Dick" alluded to in this metaphor was Richard Cromwell, "Lord Protector" of England for…
