Professor Jacob Lorch and Mrs J Cussens both believe that history justifies the apparently perverse behaviour of Americans in going back before they go forth. The vast majority of Americans are descendants of immigrants, with an natural tendency to go back. 'Surely in Inuit', says Professor Lorch, 'it would be forth and back.'
Tim Nicholson also blames history, but for a different reason: 'As anyone who has ever seen a Wild West film knows, the wise guys usually back off a few paces, six-shooters at the ready, before cautiously moving forward again.'
Nobody suggested that the double- door problem - pushing when you should pull and vice versa - might be caused by the doors being operated by to-and-froing Britons after having been installed by back-and-forthing Americans.
Instead of that rather simple explanation, we have a variety of suggestions. Many readers have offered advice, which summarises as: Pull on the door with the keyhole if entering, push if leaving a building. It is dependent on fire regulations and the way doors lock.
The most convincing rationale comes from Christopher Finch: 'We push doors instead of pulling, and vice versa, because of our earliest experience. The midwife shouts 'push', but we are then pulled. We never recover from this trauma and from then on nothing is as it seems. Doors shut in our face, that which appears open is closed . . . .'
G Q Simpson, whose double-door problem is now, we hope, solved, returns with another anxiety: 'Why do people refer to searching with a fine tooth-comb instead of a fine-tooth comb?'
Any information on the history, design and applications of tooth- combs would be gratefully received.
Answers would also be appreciated to the following:
'We all know that hot air rises, so why does it get colder the higher up you go in the atmosphere?' (Robert Young)
'Given the vast number of tins of oxtail soup produced every year, why do you never see the great herds of oxen needed to make it. And what happens to the rest of the ox?' (Nick Kimber)
And finally, Amanda Cottam would like to know: 'Why does it always rain when I wear one particular pair of brown shoes?'
All replies to Silly Question, The Independent, 40 City Road, London EC1Y 2DB.