GOOD QUESTIONS / Waking up a little taller

What does the D in D-Day stand for? (Mrs S Morrison, Glasgow)

There are three theories - implausible, speculative, and dull but probably true. The implausible one is that the date was postponed three times, the abandoned days having been referred to as A, B and C. Quite apart from the fact that military historians mention only one postponement - from 5 June until 6 June 1944 - the idea of celebrating anything called B-Day is too lavatorial to consider.

The speculative theory is that D is for Deliverance or Decision. Unfortunately there is no evidence anyone suggested it at the time. Such ideas are post hoc rationalisations from people yearning for the D to stand for something.

The only convincing answer is that it stands only for Day. Since the First World War, and perhaps earlier, it has been customary to refer to the time of a military operation as H-Hour on D-Day, particularly during the planning phase when the precise date is undecided or secret. H minus 2 or D plus 5, for example, may then be specified by reference to the zero hour.

While H-Hour lacks the decisiveness of D-Day, it does at least avoid the potential confusion of T-Time.

When and how did pikestaffs become plain? (James Rogers, Seaford, East Sussex)

In 1591, when Robert Greene wrote A Notable Discovery of Coosnage. The phrase 'plain as a packstaff' had been around at least 50 years earlier, a packstaff being the plain rod on which a traveller may carry his pack. The pikestaff - a walking stick or weapon handle - was less plain than a packstaff, although still considerably plainer than the average ceremonial staff of office. The changed form, of which Greene is credited with the first use, may have supplanted the old as more euphonious - the long vowel of pike matches that of plain.

Apart from being noted as a feckless drunkard, Robert Greene is remembered for providing the first recorded reference to Shakespeare, whom he described as an 'upstart Crow, beautified with our feathers.' Greene's Pandosto was the source for Shakespeare's The Winter's Tale. He is said to have died of a surfeit of Rhenish wine and pickled herrings, but it was probably plague.

Principal sources: OED and Oxford Companion to Literature.

Why do many World War I memorials refer to 1914-19, rather than 1918? (David Hyatt, London E8)

Although the fighting ended with the armistice on the western front on 11 November 1918 and the surrender of the German fleet 10 days later, the war only ended formally with the signing of the Treaty of Versailles on 28 June 1919.

Why do one's feet seem further away when lying in bed than they do when standing up? (Geoffrey Langley)

We asked several psychologists and one neurologist this question, and they were unable to agree even whether it was true. The neurologist lay down to try it, then rose and excitedly asked whether there were enough people in the room to do an experiment and write a paper. Anyway, four theories have emerged.

1: There is a natural tendency, caused by the shrinking effects of perspective, to overestimate horizontal distances compared with vertical ones. This is a well-documented illusion, though has not, as far as we are aware, even been applied to the eye-foot distance. In theory, though, it could predict that when lying down, one's feet would appear further away than when standing up.

2: Most people would like to be taller. Body-image is always likely to differ from true body-shape in the direction of ideal body-image. Therefore, most people strive to believe they are taller than they really are. This delusion is easier to sustain when lying down, and not faced with the obvious and dream-shattering comparison with other people.

3: Your feet are further away when you lie down. When standing, the weight of the body and head causes depression of the spine, resulting in a loss in height (although it may only be around 1mm). Most people wake up taller than when they went to bed.

FEEDBACK: Geoffrey Langley writes to correct an item we had a few weeks ago, concerning Sod's Law and Murphy's Law: 'Sod's Law doesn't read 'If anything can go wrong it will', but 'If anythign can go wrong it will'.'

Further mysteries may be sent to: Good Questions, The Independent, 40 City Road, London EC1Y 2DB.