There are two main types of smoke alarm tech, says Raman Chagger, principal consultant at BRE, the Building Research Establishment. Ionisation-based systems use a tiny amount of radioactive material to charge, or ionise, particles in the air which flow between two small plates. Should smoke interrupt that flow of charged particles, the alarm goes off.
First writing may be 40,000 years earlier than thought.
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When I was talking about the power of smell on the radio, Speth, a Welsh speaker from Manchester, got in touch to say that in Welsh you can hear a smell as well as smell it. At first this sounded charming, if far-fetched. But the more I thought about it, the more sense it made. While I can’t – in English, anyway – exactly hear the smell of that Black Country bike shop in 1977, I can smell, hear and see it very clearly. I can feel it too. I can feel the shop man’s grip as he lifts me into the saddle. And I can hear him saying to my grandad: “Blimey, he’s a lump, isn’t he?” Ever sensitive about my weight, that was a sour note. But I’ll let it pass, because all I can feel, then and now, is the general joy.