Disposable cups made from insulating polystyrene stop hot drinks from burning your hands. But there is no way to tell whether the contents are so hot they will burn your mouth and throat at first gulp. Mandy Haberman of Radlett, Hertfordshire, in the UK has come up with a delightfully simple answer (WO 03/061439).
Her disposable cup has a small window in the side, just beneath the cup lip. The window is covered with a thin flexible sheet of polyester that conducts heat well. Before you take a sip, gently tip the cup just enough for the liquid to…
