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We advise you to purchase a paperback edition of the novel. It is much more comfortable to read a novel in bed than sitting at a desk, reading from a computer monitor.
However, the integral text of Les Misérables is available online, both in the original French as well an an English translation.
Avoid printing the book at home from online sources. Not only you'd waste much more paper than by purchasing a paperback copy, but you'd also spend more money on paper and ink!
Generally speaking, whatever the book being translated, there are two types of translations. The first type stays very close to the literal lexical and grammatical structure of the original. It can be said to be "faithful" to the letter of the original, but the translation might lack the poetic resonance that the original might have had. The second type takes more liberties towards the original text to be more in accordance with the intricacies of the target language. It is a less literal translation but one that attempts (even if not always succeeds) are being more faithful to the spirit of the original. Which is best? It depends on personal taste, although if your purpose is to learn the original language, a more literal translation might be more helpful.
We shall complete this wiki page as we learn of new translations. They are ordered by year of first publication (if known).
 Lascelles Wraxall: He produced the first British translation of Les Misérables.
Wikipedia article: Frederic Charles Lascelles Wraxall.
 Isabel F. Hapgood is the translator of the New York, 1887 edition. It appears to be the source of all free/cheap paperback and electronic editions.
Wikipedia article: Isabel Florence Hapgood.
 Norman Denny: an abridged British translation, said to be about 100,000 words shorter than the Julie Rose translation 3.
 Lee Fahnestock and Norman MacAfee: a modern American update of the original Wilbour translation.
 Julie Rose: her translation takes more liberties with the original text4.
See this nicely done Translation comparisons, which compare an short section of the original French to four translations.
Many English paperback editions of the novel are abridged and excise the long Waterloo section of the novel. For the purpose of this project, it is best to make sure to get an unabridged edition.
Please let us know which paperback editions exist. Are they illustrated? Annotated? Which translation? How many volumes (two or even three volumes may be more portable than a single one).
* Wordsworth Classics edition (2 vol): inexpensive (unabridged original translations, wilbour?) It has a good introduction, and helpful notes in each volume explaining obscure references, and a short bibliography. Intro & notes by Roger Clark, U of Kent at Canterbury.
* Signet Classic paperback edition: unabridged Fahnestock translation.
You can find free electronic unabridged editions for EPUB, Kindle, Plucker, QiOO at the Project Gutemberg (Hapgood, 1887).
Google books has the 1862 Wilbour translation.
Electronic editions are also available for around $3 at Amazon.
In order to quote some text in your comments and blogs, the text published at wikisource (Hapgood, 1887) is the most convenient because it is easily browsable.
If you wish to learn French and attempt to read the novel in the original language, this site will publish online the text with French and English facing each other. Chapters will be published progressively, together with the series of blog entries discussing the novel.
We don't know yet of any paperback edition with both English and French, although, obviously, you can purchase two different editions, one in French and one in English.
You can also freely download the French audiobook . This is a very nice reading and a recommended download if you want to improve your French!
Évidemment, le nombre d'éditions française est très élevé. On ne saurait en faire une liste complète. Voici tout de même les éditions que nous connaissons:
* Éditions Le Livre de Poche, en deux volumes (9633 et 9634), avec en couverture des photos du film de 1998 avec Liam Neeson. L'édition, abondamment annotée, contient une préface et 40 pages de notes de Guy Rosa ((c) 1998) ainsi que 20 pages de commentaires de Nicole Savy ((c) 1985).
Le texte complet de l'édition originale est disponible pour EPUB, Kindle, Plucker, QiOO au Project Gutemberg.
Le texte publié à wikisource est plus pratique pour naviguer et citer quelques passages dans vos commentaires.