Argand’s lamp

I once plunged a lecture theatre into darkness. Pandemonium ensued. There were shouts, chatter, whistles, laughter, hoots – even some missiles – in truly inky blackness. It was a striking demonstration of how unusual it is for us to be truly in the dark, and how unsettling that darkness can be.

The fear of the dark goes back a long way and with good reason. Most cities were once no go zones after sunset – anyone foolish enough to walk ran the risk of robbery, violence or worse. The problem was so bad that in October 1524 the French parliament issued an edict requiring each household to maintain a candle or lantern to cast light into the street. This was followed by another order requiring a man to be stationed with a lamp or light at the corner of each road. By 1664, Louis XIV issued letters patent approving a corps of porte-flambeaux or porte-lanternes – torch or lantern bearers – who, for a fee, would escort and protect those needing to travel in the hours of darkness. The success of this service led to fixed lanterns in Paris, maintained by a team of éclaireurs publiques who would light the tallow candles in the evening. Travellers from abroad marvelled at the glass boxes suspended above the road.