There is a well-thumbed copy of Rebecca Wells's Divine Secrets of the Ya-Ya Sisterhood lying in the foyer of the Traverse Theatre in Edinburgh.

Pasted inside the front cover is a note that says: "Please read me. I'm not lost. I'm travelling around trying to make friends."

In Glasgow and Aberdeen, there are similar books being mysteriously left on park benches, in charity shops and even in supermarket car parks.

Each beseeches the reader to "read and release" and is part of a global sociology experiment spearheaded by the web site www.bookcrossing.com. Already boasting 18,000 members in North America, the craze has begun to take hold in the UK, with more than 200 books now released across the country, proving that books and the digital age can co-exist.

Part book club, part message-in-a-bottle experiment, the idea encourages people to register books on the website and then deposit them in public places, such as coffee shops and aeroplane seat pockets.

Each book that is registered, at no cost, receives an identification number and registration card - attached inside the front cover - directing anyone who finds a book towards the online site. There, readers can detail where the book was found and thoughts on its content. In keeping with the book-crossing philosophy, finders are then encouraged to release the book "into the wild" for the next readers to enjoy.

"It harks back to childhood memories of message-in-a-bottle or letting go helium balloons," said Ron Hornbaker, the Kansas City-based computer consultant who founded the scheme. "Readers in general are generous people, and giving something they love to the world and letting fate and serendipity take over is fun.

" His dream is to turn the world into a global library - he detests the sight of books gathering dust on a shelf.

"I looked at my full bookshelf and thought, 'What good are they doing there?'. Some people read books more than once; I rarely do. This makes it fun to give them away, rather than just a book drop at a library, and allows people to have some connection with a book even after it is gone."

The site was launched in April 2001, but received only a modest response until it was picked up by the US media four months ago. Now, book-crossing texts have been reported in 40 countries and the site has gained 200 members a day, 60 per cent of whom are female.

One of the first members in Scotland was Duncan Cumming, 27, an IT manager from Glasgow, who has released three books in the city, two in the Oxfam shop in Byers Road and in a park in the West End.

He said: "I think it's a cool idea to pass a book on to someone else and see where it goes. I would love to know what has happened to them."

The website reveals 15 books have been released in Scotland, in places as diverse as the Safeway car park in the Almondvale Centre, Livingston, Cloisters pub in Edinburgh and in the Candle Close Gallery in Aberdeen.

Currently, in Gallagher's pub on Ross Island, Antarctica, there is a copy of Cod: A Biography of the Fish that Changed The World. In the Cafecito restaurant, Azuay, Ecuador, the Sue Grafton mystery E is for Evidence is waiting for its next reader.

Bibliophiles, however, must accept that some people may find a book and choose just to keep it, or even sell it.

Tess Crebbin, a Canadian author, tried to leave a copy of Helen Fielding's Bridget Jones: The Edge of Reason in a popular sushi bar in Munich. "I left the restaurant and all of a sudden there's this commotion and a Japanese waiter is chasing me down the street saying, "You left your book!' "I told him, 'take it back.' He looked at me like I was crazy."

Ian Rankin, the author of the Inspector Rebus books, said: "I think it's brilliant and it is part of what we have always done.

"Anything that involves sharing books around is good."

The '3 Rs' of Bookcrossing Read a good book. Register it at bookcrossing.com www.bookcrossing.com, obtain a unique BCID (Bookcrossing ID number) and label the book. Release it for someone else to read. Leave it on a park bench, in an aircraft seat pocket, or donate it to charity. You are notified by e-mail if someone finds the book and registers it.