Skip to content
Vatican Observatory
  • About
    • Overview
    • Team
    • FAQ
  • Telescopes
    • Overview
    • Telescope Images
  • Tours
    • Castel Gandolfo
    • U.S.
  • Latest
    • Overview
    • Resources
    • Press
    • Audio
    • Video
    • Research
    • Authors
      • FAQs
    • Newsletter
    • Tucson Meteor Cameras
  • Podcast
  • Education
    • Overview
    • Resource Center
    • Image Gallery
    • Summer School
    • Books
    • Software
    • Additional Resources
    • ACME
  • Shop
  • Calendar
    • View our Event Calendar
  • Donate
    • Donate Now
    • Smart Ways to Give
    • Sacred Space Astronomy
      • View Content
    • Bequests / Trusts
    • The Foundation
      • Newsletters
      • Annual Reports
  • Press
    • VO in the News
    • Press Kit
  • Specola Vaticana
  • Contact
    • Contact
  • About
    • Overview
    • Team
    • FAQ
  • Telescopes
    • Overview
    • Telescope Images
  • Tours
    • Castel Gandolfo
    • U.S.
  • Latest
    • Overview
    • Resources
    • Press
    • Audio
    • Video
    • Research
    • Authors
      • FAQs
    • Newsletter
    • Tucson Meteor Cameras
  • Podcast
  • Education
    • Overview
    • Resource Center
    • Image Gallery
    • Summer School
    • Books
    • Software
    • Additional Resources
    • ACME
  • Shop
  • Calendar
    • View our Event Calendar
  • Donate
    • Donate Now
    • Smart Ways to Give
    • Sacred Space Astronomy
      • View Content
    • Bequests / Trusts
    • The Foundation
      • Newsletters
      • Annual Reports
  • Press
    • VO in the News
    • Press Kit
  • Specola Vaticana
  • Contact
    • Contact

From the Cabinet of Physics: The Coherer Jumps to Attention

By Bill Higgins  |  27 Aug 2016

Share:
  • Share on Facebook
  • Share on Twitter
  • Share on LinkedIn
  • Share via Email

This entry is part 5 of 23 in the series From the Cabinet of Physics

At the end of the Ninteenth Century, one exciting technical development was the study and application of “Hertzian waves.” Physicists learned that the intimate link between electricity and magnetism allows invisible waves to be generated and, some distance away, detected.

Among the instruments in the Cabinet of Physics are quite a few associated with this revolution, which led to the “wireless” or “radio” industry. Today’s video portrays the coherer, a key device in the detection of radio waves.

The coherer is a glass tube that holds iron filings or other metal. Ordinarily it is a poor conductor; when it is in circuit with the Grenet-cell battery on the right, a galvanometer detects negligible current flow through the circuit.

But if a suitably powerful Hertzian wave passes through the room, the tiny filings can be jerked into alignment. Suddenly the coherer is a good conductor, and the needle of the galvanometer is deflected.

Supplying the invisible radio wave are the supporting players in this drama, seen on the left: Leiden jars, the wheel-like Wimshurst machine that charges them, and the brass spheres of a spark gap.

The coherer is awkward to use; after each detection, one must tap the tube to jiggle the metal filings, so they again become a lousy conductor. Nevertheless, this invention enabled the first generation of wireless to move from laboratory apparatus to commercial success. I imagine that many of the Italian students witnessing this demonstration went on to careers in the new radio industry.

The Foundation for Science and Technics, or Fondazione Scienza e Tecnica, of Florence, Italy, has made available many videos exploring the Cabinet of Physics, a large collection of antique scientific demonstration instruments.  The Foundation’s homepage may be found here, and its Youtube channel, florencefst, here.

Share:
  • Share on Facebook
  • Share on Twitter
  • Share on LinkedIn
  • Share via Email

Sacred Space Astronomy

The Vatican Observatory’s official digital community and online magazine.

Become a Member

Recent Posts

Visit of Br. Guy Consolmagno S.J.

Pluscarden Abbey  |  19 May 2025  |  Press

The Skull of St. Thomas Aquinas, Realities, and Science

By Mr. Christopher Graney  |  17 May 2025  |  Sacred Space Astronomy

From the Backyard: Pope Leo XIV, Leo XIII, Rerum Novarum and AI

By Fr. James Kurzynski  |  12 May 2025

Ellerman Bomb

11 May 2025  |  Sacred Space Astronomy

Archives

      • May
      • April
      • March
      • February
      • January
      • December
      • November
      • October
      • September
      • August
      • July
      • June
      • May
      • April
      • March
      • February
      • January
      • December
      • November
      • October
      • September
      • August
      • July
      • June
      • May
      • April
      • March
      • February
      • January
      • December
      • November
      • October
      • September
      • August
      • July
      • June
      • May
      • April
      • March
      • February
      • January
      • December
      • November
      • October
      • September
      • August
      • July
      • June
      • May
      • April
      • March
      • February
      • January
      • December
      • November
      • October
      • September
      • August
      • July
      • June
      • May
      • April
      • March
      • February
      • January
      • December
      • November
      • October
      • September
      • August
      • July
      • June
      • May
      • April
      • March
      • February
      • January
      • December
      • November
      • October
      • September
      • August
      • July
      • June
      • May
      • April
      • March
      • February
      • January
      • December
      • November
      • October
      • September
      • August
      • July
      • June
      • May
      • April
      • March
      • February
      • January
      • December
      • November
      • October
      • September
      • August
      • July
      • June
      • May
      • April
      • March
      • February
      • January
      • December
      • November
      • October
      • September
      • August
      • July
      • June
      • May
      • April
      • March
      • February
      • January
      • December
      • November
      • August
      • June
      • March
      • January
      • November
      • October
      • December
      • November
      • April
      • May
      • January
      • December
      • September
      • May
      • March
      • December
      • November
      • February

More Posts in this Series:
"From the Cabinet of Physics"

Nature’s “Where I Work” Photography Exhibition at King’s Cross Shows Br. Guy Consolmagno

By Robert Trembley  |  23 Apr 2024  |  Sacred Space Astronomy

Press Release: New cosmological research of the Vatican Observatory

By Robert Trembley  |  26 Mar 2024  |  Sacred Space Astronomy

“Faith in Science: Catholic and Jewish Perspectives on Creation and the Cosmos.”

YouTube  |  6 Nov 2023  |  Press

Seeking God in science is part of Jesuit’s vocation

YouTube  |  25 May 2022  |  Press

Newsletter

Upcoming astronomical events, scientific breakthroughs, philosophical reflections… just a few reasons to subscribe to our newsletter!

Vatican Observatory
  • About
  • Telescopes
  • Tours
  • Latest
  • Podcast
  • Education
  • Shop
  • Calendar
  • Donate
  • Press
  • Specola Vaticana
  • Contact
Privacy Policy  |   Cookie Policy  |   Disclosure Statement  |   This website is supported by the Vatican Observatory Foundation

Podcast:

  • Apple Podcasts Listen onApple Podcasts
  • Spotify Listen onSpotify
  • Google Podcasts Listen onGoogle Podcasts
  • Stitcher Listen onStitcher
  • Amazon Alexa Listen onAmazon Alexa
  • TuneIn Listen onTuneIn
Made by Longbeard