Induction Coils

Straight spark gaps…there’s a variety of them in here…there are also induction coils…and this is a Crooke’s tube. And here is the first example of a cathode-ray tube, a Braun tube.

Moving over here is a display of Geissler tubes.  There are also Geissler tubes up on the back…those squiggly things, which are essentially the same thing as neon signs today.  They date almost back to the Civil War time.  It could be even before the Civil War.  Those particular ones are very early.  They were done for demonstrating peculiar effects.  They had no other purpose.

This is a cold cathode-ray tube.  There’s no filament in it, and the screen is the white metal plate.  I can exercise, or energize this with high voltage.  The curving of the beam is caused by the horseshoe magnet in the rear.  The poles are facing this way.  If I turned that around, the beam would go the other way.

Fred – “Some of this stuff is on the transmitting side…all these sparks, is that right?”

Yes, but many of them are just demo sparks, but otherwise, transmitting sparks.

There’s a quenched-gap plate…

Fred – “Whereas this cathode ray tube was on the receiving side?”

That was a laboratory curiosity.  That’s very early.  That’s the first example of a cathode-ray tube, and we should really carry from there, across the hall, because the evolution of the cathode-ray tube is in this Braun tube.  Everywhere in the world, at least in my younger years, everywhere in the world, the cathode-ray tube was known as a Braun tube…the Braunschen Röhre, and that’s in honor of Karl Ferdinand Braun, who was the inventor of the Braun tube.

Professor Chaffee at Harvard, who I mentioned before, also gave us this tube, which he had ordered specially from Germany, I believe in 1913.  And that’s a very rare article, and it’s quite impressive because it has all of the same elements as the 1930 Western Electric equivalent.  You see the X and Y deflection plates here, on the Western Electric, they’re much smaller, but they do the same thing.  The focusing electrodes…they’re all the same, but Western Electric made these…

Text from the transcript of a tour of New England Wireless & Steam Museum’s Wireless Building given by Robert W. Merriam on a winter day in 2012. Transcription by Craig H. Moody, K1CHM. Edited by Fred Jaggi.