You can read a contemporary account of the moment Sir Isaac Newton stumbled upon the theory of gravity online.
The Royal Society has made manuscripts of a biography of Newton available on its website to celebrate its 350th anniversary this year.
"It was occasion'd by the fall of an apple, as he sat in contemplative mood. Why should that apple always descend perpendicularly to the ground, thought he to himself," the manuscript, written by Newton's biographer William Stukeley, reads.
The Royal Society has also digitised several other works of historical note, including the 1681 Constitution of Carolina, sketches of fossils made by Sir Henry James in the 19th Century and a letter from Thomas Paine regarding the construction of a bridge made from iron.
You can access the documents on the Royal Society website, including a 3D version if you have .NET Framework 3.5 installed on your PC.
Otherwise, to see the documents you will need to have the Silverlight plug-in for your browser.
http://royalsociety.org/Turning-the-Pages/