Several however, jumped to the conclusion that we had erred and had meant to say a defunct light bulb. A used light bulb is, of course, a bulb that dispenses used light by recycling second-hand photons. This is how photographers obtain atmospheric shots. Since nobody quite appreciated the scientific subtlety of the question, here are some uses for a defunct light bulb.
The most frequently suggested were as a darning mushroom, crystal ball, ecologically-sound energy-saving device, display case for small animals, garden frame for bonsai tree or small plant.
Several suggested incorporating it into a entry for the Turner Prize (as indeed they also did with odd socks and wire coat-hangers).
Geoffrey Langley provides the most detailed specification for an artwork, with the light bulb, an exhausted toothpaste tube, a brick or two and a few banana skins combining to form a creation called 'HM Government 1993' to be sold to the Tate Gallery.
Here are some other ideas:
Mood lighting for a romantic evening - a householder's version of 'I've run out of petrol' (Andrew Middleton).
Plugging mole-holes without depriving the animals of daylight (S Comberti).
Cut the bulb in half for a perfect avocado dish (Ian Wolstenholme) or remove filament and move metal fitting to other end for a delicate glassware drinking vessel (Daniel Atrill).
A new emblem for the Conservative Party in place of the torch (Mrs F Rosner).
Export to polar regions for use during the endless summer days (Dan Jameson) or use as a navigational device marking out lines of latitude and longitude (Robert and Sarah Reynolds).
Paint it red and use it as a recall light for next year's Grand National (Scott Marshall).
Goldfish bowl for small fish or sterile housing for mice with infectious diseases (Lindsay Warden); diving helmet for voles or flying helmet for birds (Rhodri Edwards).
The most scientifically creative suggestion comes from Martin Brown, who writes: 'When electric light is not needed, simply remove the working lightbulb and replace with a used one (and vice versa when light is wanted. This eminently sensible utilisation would enable everyone to dispense with unsightly light switches and all the associated wiring.'
For sociological awareness, however, our dead light bulb award goes to Paul Waters' use as 'teddy bears for skinhead co-dependency groups'.
This week's object is an empty toothpaste tube. (No works of art, please.) Suggestions to Creativity, the Independent, 40 City Road, London EC1Y 2DB.Reuse content