Handing a farmer a fistful of magic beans with the promise that they will improve his business might sound like something out of a fairy-tale. But, as Arthur C. Clarke put it, any sufficiently advanced technology is indistinguishable from magic. The sensor-filled “beans” developed by Andrew Holland, an electronics engineer from Swaffham Bulbeck, near Cambridge, England, are not only advanced technology. They could also, Mr Holland says, provide an answer to many a farmer’s prayers. Mixed into the contents of a granary, his beans would report continuously on the temperature and humidity, both of which encourage rotting if they are too high, and on carbon-dioxide levels, which reflect the amount of insect breath exhaled, and thus the level of infestation.