I read that Benjamin Franklin built the Franklin's bell using a long vertical rod connected to one bell, and another one connected to another bell and then going in the ground.

I did build a Franklin's bells machine and works nicely, but I have to create the electrostatic potential.

How did Franklin build his own machine at that time? How high was that rod in the sky? What are the dangers in doing this (I guess it is potentially dangerous using it during a storm with lightings in case I catch one and I touch the rod).


1 Answer 1


A quick run around google suggests that all you need is a rod that is above the house and a wire down to the bells. The rod and wire must be insulated.

Don't use it anywhere important (say, your house.)

If the long rod is grounded, then the bells won't work.

If the rod isn't grounded, and lightning strikes, then your bell device will conduct the current down closer to the house and ground.

You will have made your house into a better target for lightning.

A lightning strike might set your house on fire.

Lightning won't have any trouble jumping the distance from your bells to the ground, but will make an awful mess doing so.

  • \$\begingroup\$ Thanks! If I'm not wrong, a lighting is not required to start the bells ringing, right? I think there should be enough electrical negative charge on the top side and then the bells will ring. But still, how long should that rod be? \$\endgroup\$ Commented Aug 17, 2016 at 3:14
  • \$\begingroup\$ @IonicăBizău - Lightning is not required, right. But the wire "antenna" depends on earth's electric field (very roughly 100v/m), which is highly distorted by adjacent trees, buildings etc. and by atmospheric conditions. Rain or snow can bring charges down from above more rapidly. I would add to JRE's suggestion, "above nearby structures, trees". And be careful, pushing ungrounded wires up into the sky creates dangerous voltages. \$\endgroup\$
    – glen_geek
    Commented Sep 15, 2016 at 14:51

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