The Phoenicians chipped theirs on stone tablets and Samuel Pepys penned his in an encrypted shorthand, while generations of schoolgirls learnt to keep theirs padlocked.

Now an anonymous blog in cyberspace has vastly overtaken the diary as the first choice for young people who wish to project their innermost thoughts while retaining their privacy. The revelation has led to fears that this historical source and literary form, exemplified by the diaries of Boswell, Coleridge, T. E. Lawrence and others, is dying a death.

A survey of 1,019 teenagers suggests that almost half write blogs while fewer than one in ten keeps a traditional pen-and-paper diary.

Jamie Andrews, head of Modern Literary Manuscripts at the British Library, told The Times: “The unguarded intimacy that results from the private relationship between writers and their diaries has made their survival critical for scholars of literature.”

The British Library is working with several organisations to collect blog archives and encourage authors to archive their posts. According to the survey, commissioned by Sky's Young Journalist Awards, teenagers believe that internet Ludditism and the use of a pseudonym would prevent parents or teachers finding their blogs. Few were worried about their safety online. The average teenager spends 4½ hours a week blogging or visiting sharing sites such as MySpace, compared with two hours reading books. Teenager blogs covered daily events, popular culture and world events.

Noted journals

“I did see the houses at that end of the bridge all on fire, and an infinite great fire on this and the other side the end of the bridge; which, among other people, did trouble me for poor little Michell and our Sarah on the bridge". Samuel Pepys September 2, 1666

“I've reached the point where I hardly care whether I live or die. The world will keep on turning without me, and I can't do anything to change events anyway." Anne Frank October 9, 1942

“We shall stick it out till the end, but we are getting weaker, of course, and the end cannot be far. It seems a pity but I do not think I can write more." Captain Scott’s final diary entry on March 29, 1912

“I take up my pen once again to record a momentous time in the affairs of men (and, thank God, because this is intended to be a secret diary, I am not required to add ‘and women’)." Adrian Mole: The Cappuccino Years by Sue Townsend

“11:45pm Ugh. First day of New Year has been day of horror. Cannot quite believe I am once again starting the year in a single bed in my parents’ house. It is too humiliating at my age." Bridget Jones’s Diary: A Novel by Helen Fielding

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