Notes and comments scribbled by naturalist Charles Darwin on the pages and in the margins of his personal library have been made available online for the first time.

Darwin's personal scientific library, the majority of which is held at Cambridge University Library, has been digitised in a collaborative effort involving Cambridge, the Darwin Manuscripts Project at the American Museum of Natural History, the Natural History Museum, and the Biodiversity Heritage Library.

A release by the University of Cambridge said that in total, Darwin's library amounted to 1480 books, of which 730 contain abundant research notes in their margins.

These annotated books are now in the process of being digitised.

The first phase of this project has just been completed, with 330 of the most heavily annotated books launched online at the Biodiversity Heritage Library for all to read at http://www.biodiversitylibrary.org/collection/darwinlibrary.

"The Darwin collections are among the most important and popular held within Cambridge University Library. While there has been much focus on his manuscripts and correspondence, his library hasn't always received the attention it deserves ? for it is as he engaged with the ideas and theories of others that his own thinking evolved," University Librarian Anne Jarvis said.

The release added that because Darwin's evolutionary theory covered so many aspects of nature, reading served him as a primary source of evidence and ideas.

Darwin once complained that he had become a 'machine for grinding general laws out of large collections of facts'.

The pages of Darwin's Library give a direct view of the great Darwinian intellectual machine in action.

With the Charles Darwin Library online, now everyone can retrace how Darwin systematically used reading to advance his science.

Most of Darwin's personal library rests at Cambridge University Library and at Down House.

Although the majority of the books are scientific, some are humanities texts on subjects that Darwin transformed into scientific topics.

The series of transcriptions accompanying each page allows everyone to see which passages Darwin found relevant to his work, stimulated his thinking, or just annoyed him as he read the work of others.

The online transcribed marginalia relies on the work of two scholars, Mario A Di Gregorio and Nick Gill, published in the 1990s and now greatly enhanced by Gill.

In addition to images of the books and transcribed jots, the information is fully indexed so that people can search for topics and ideas relevant to their interests or work, the release added.