Beschreibung:

FOUCAULT DISCUSSES HIS GYROSCOPE.FOUCAULT, JEAN BERNARD LEON. 1819-1868. Autograph Letter Signed ("L. Foucault"), 4 pp, 8vo, London, October 19, 1854, to Madame Thompson, in French.
French physicist Leon Foucault, known for the Foucault pendulum which provided clear evidence of the effect of the Earth's rotation, and which he further demonstrated with his gyroscope, writes to Madame Thompson just a week before he would demonstrate the gyroscope to Prince Albert at Windsor Castle. ["The gyroscope continues to be of sure success...."]
Foucault's pendulum was first demonstrated in the Meridian of the Paris Observatory and then more famously the Pantheon in Paris when he hung a 62-pound brass-coated lead bob on a 220-foot wire from the dome and showed that over a period of 31 hours, 50 minutes, the plane of the pendulum's swing made a full clockwise circle, thus demonstrating the Earth's rotation.
The experiment caused a sensation and Foucault pendulums were set up in major cities throughout Europe and America.
His gyroscope was conceived as a better contained demonstration of this same phenomenon. Where the Foucault pendulum would take many hours to work through its full course, the gyroscope could provide evidence of the Earth's rotation within the 8 to 10 minutes before it slowed.
Foucault was at the height of his powers at the time of this letter. He would be awarded the Copley Medal by the Royal Society for his "very remarkable scientific researches," and would discover eddy currents the following year.