The Lightning Rod: Give the Strike a Path That Survives It

Charge the Leyden jar. Bring a smooth ball — a metal ball on an insulated handle — slowly towards its terminal: nothing happens until it is close, then a single sharp spark jumps. Charge the jar again and bring a needle, held on an insulated handle and wired to earth, slowly towards it, point first. In the dark you may see a faint glow at the point and hear a hiss; there is no big spark, and when you then test the jar with the ball, it is nearly discharged. The point drew the charge off quietly. That is the 'power of points' Franklin reported. A modern rod works mainly by where it stands and how well it is earthed; the notebook shows why the wire matters more.

**Benjamin Franklin** proposed the pointed, earthed rod in a letter of 1750 and published it in *Poor Richard's Almanack* for 1753; rods were in use from 1752. No patent exists — Franklin declined to patent any of his inventions. Modern lightning protection (IEC 62305 and its equivalents) keeps his three parts — air terminals, down-conductors, earth electrodes — and sizes them from the stroke statistics the notebook uses. **Honest limits.** A rod protects a zone, not a whole landscape. It does not prevent surges entering along wires and pipes, which need their own protection. And it is only as good as its earth connection and its joints. **Never experiment with atmospheric electricity** — Georg Richmann was killed in 1753 repeating Franklin's experiment.