Silly Question: Read this in only an hour

SECONDLY, asks R Bannerman, what other words cannot reasonably be used to begin newspaper columns? But firstly, let us precede to two definitive answers to earlier queries, writes William Hartston.

Jeremy Shaw explains, as a practitioner of direct marketing, why adverts always say 'allow 28 days for delivery' instead of 'a month'. It is all in Rule 431 of the Advertising Copywriters' Rulebook: 'Always use small units of measurement to make things seem smaller and big ones to make them seem bigger.'

'That's why you'll 'learn a new language in only 90 days' (heaven forbid it should take three whole months) but a guarantee will always be for 'a full year', never 365 days. And finally,' he concludes, 'I can claim an unimpeachable antecedent. After all God didn't take a whole week to create the earth, just seven days.'

But Mr Shaw, who clearly includes unpaid holidays in his estimates, would still like to know why signs say 'Road works' only when it doesn't.

Naomi Tarrant, Curator of Costume and Textiles at the Royal Museum of Scotland, has written with a definitive account of the history of male and female styles of jacket fastening. Her researches indicate that Western men have always been predominately left-over-right fasteners.

'It has been suggested that the origin lies in cloaks being fastened to allow the right arm, which held the sword, to be free.' The Chinese have also always preferred left-over-right. 'It may be that as humans are predominately right-handed this method of fastening allowed the right hand access to the chest area.' So that it is easier to scratch, presumably.

In the mid-17th century, women started wearing men's coats as riding habits. They buttoned the same way until the mid-19th century, when 'the convention appeared to develop of women's clothes being fastened in the opposite direction. By 1900, women were buttoning everything right-over- left. The explanation may be the Victorians' greater concern to denote male from female clothing.'

Next week we shall explain why kamikaze pilots wear crash helmets. This week's questions: Why are biscuit tins not quite square? (Lucy Whittle, who can never get the lid on the right way.) Why can one no longer buy yellow lavatory paper for one's yellow bathroom? (Daisy Herrman.) Why do questions always look better in groups of three? (Ian McLauchlin.)

Answers and more questions to: Silly Question, The Independent, 40 City Road, London EC1Y 2DB.