DUET RIDDLE  5
For anyone with absolutely nothing better to do, this has been online since April 16th, 2005

NEWS! This riddle was finally cracked on 1st January, 2008 when an ex-student mailed the correct solution 
to us.He wins a prize - but the solution will not go online, so others can play at trying to crack it too.
 

A Comet, A Boy and Three Books

The appearance of a comet (now known by name) so bright that it could be seen in daylight seemed ominous in an ill-fated year: King A died in January, aged 63. King B, his successor, died in October of the same year, aged 44, and his country took on the nationality of King C. But King C successfully lived another 21 years. The comet's name, without the addition "comet".

Jean-Jacques Rousseau the philosopher  thought certain experiences (like reading  Book 3) were necessary for every child  to develop a healthy and imaginative  attitude to life.    The name of his fictitious boy child. +++++

Book 1 was commissioned by King C. He had it written in Latin and made sure it was not a work of fiction - that would have defeated its purpose. The book is the world's oldest surviving one of this kind, and more than 900 years old. Its content is now available online, too. The name of the book, without the addition "book".

Book 2, thought to be the world's largest, has almost 730 very hard-wearing pages all housed individually in a beautiful palatial mound built between 1860 and 1869, and the writing on them originally had gold leaf decoration. Like Book 1, it is unique. Nobody could afford to buy it, let alone move it from its golden- tipped white-walled home. The name of the book's sacred text

Book 3 describes what a certain person did in a certain place (33° 38' 29" S, 78° 50' 28" W). When Book 3 appeared,  notions of  fact and fiction got entangled with ideas of  truth and lying but still the book was an instant bestseller. Even now, most people know of it even if they haven't read it.  It has since sparked off new books, films, theories of education - and dreams... The author's first name.

Names, names, names! Altogether, how many times do the letters A, E, I, O and U appear?