Drupal - Spliting a node into multiple pages

I suggest split your text to some part with jquery and by scrolling you append(may with some effect like fadeIn .... ) another part to main part.
I suggest you achieve this job by jquery (client side solution)

You are looking for Smart Paging module

Provides splitting up long Drupal content into sub pages by number of characters/words or by a placeholder HTML tag for node, user and taxonomy term entities.

For Drupal 6

Paging module, you can set character limit and it will automatically split in to sub pages see the below screen shot

Break long pages into smaller ones automatically by words(or characters) limit