Unlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve to be made available for future generations to enjoy.

Unlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve to be made available for future generations to enjoy.

Unlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve to be made available for future generations to enjoy.

Pell's Equation is a very simple Diophantine equation that has been known to mathematicians for over 2000 years. Even today research involving this equation continues to be very active, as can be seen by the publication of at least 150 articles related to this equation over the past decade. However, very few modern books have been published on Pell's Equation, and this will be the first to give a historical development of the equation, as well as to develop the necessary tools for solving the equation.

The authors provide a friendly introduction for advanced undergraduates to the delights of algebraic number theory via Pell's Equation. The only prerequisites are a basic knowledge of elementary number theory and abstract algebra. There are also numerous references and notes for those who wish to follow up on various topics.

Rivers were the arteries of our first civilizations - the Tigris and Euphrates of Mesopotamia, India's Ganges, Egypt's Nile, the Yellow River of China - and have nourished modern cities from London to New York, so it is natural that poets have for centuries drawn essential meanings and metaphors from their endless currents. English poets from Shakespeare and Dryden, Wordsworth and Byron to Ted Hughes, John Betjeman and Alice Oswald; Irish poets - Eavan Boland, Seamus Heaney, Paul Muldoon, to name but a few; Scottish and Welsh poets from Henry Vaughan and Robert Louis Stevenson to Robin Robertson and Gillian Clarke. A whole raft of American poets from Whitman, Emerson and Emily Dickinson to Langston Hughes, Mary Oliver, Natasha Trethewey and Grace Paley. Folk songs. African-American spirituals. Poems from ancient Egypt and Rome. From medieval China and Japan. And a truly international selection of modern poets from Europe (France, Italy, Russia, Serbia), India, Africa, Australia and South and Central America, all combining in celebration of the rivers of the world. From the Mississippi to the Limpopo. From the Dart to the Danube. Plunge in.

Pell's Equation is a very simple Diophantine equation that has been known to mathematicians for over 2000 years. Even today research involving this equation continues to be very active, as can be seen by the publication of at least 150 articles related to this equation over the past decade. However, very few modern books have been published on Pell's Equation, and this will be the first to give a historical development of the equation, as well as to develop the necessary tools for solving the equation.

The authors provide a friendly introduction for advanced undergraduates to the delights of algebraic number theory via Pell's Equation. The only prerequisites are a basic knowledge of elementary number theory and abstract algebra. There are also numerous references and notes for those who wish to follow up on various topics.