Electrolytic detector How it works Not to put too fine a point on it Commentary

Reginald Fessenden electromagnetism

Spinthariscope

• William Crookes spilled a little radium bromide
• on a screen coated with zinc sulfide.
• He noted under a microscope discrete scintillations—
• fluorescence from alpha particles emanating from the radium.
• Today the device he invented, the spinthariscope,
• is a novelty for viewing nuclear disintegrations.
• In its day it was wildly popular and led to the development
• of the Geiger counter and Rutherford’s model of the atom.

Scintillations

• Today instead of radium bromide, which is dangerous,
• spinthariscopes use americium, but the scintillations
• are objectively the same. Then, they didn’t know how dangerous
• it was. They thought it was good for you, even fun,
• not only that it made the hands of your Timex visible in the dark,
• but also that it could cure eczema and psoriasis. If they had known,
• subjectively, there could have been more to it.

Fántasmascope

• Suppose we could reconstruct
• a person’s past visual experiences
• by examining his retinas and brain.
• If so we could project these images
• on a tiny screen visible through a small lens.
• We could call them ghosts, and the Greek
• for ghost is fántasma. The only trouble is
• even though we know those images
• are in there, we cannot reconstruct them.
• If you start to see people who have passed away,
• you may be suffering from a form of dementia.
• This actually happened to someone I loved.