NEW YORK• Evan Thomas, the best-selling biographer of Robert F. Kennedy and Dwight D. Eisenhower and the author of a half-dozen other books, has seen those books reviewed over the years by The New Yorker, The Washington Post and The Atlantic.

But with the recent publication of his latest work, Being Nixon: A Man Divided, he experienced for the first time a new phenomenon: the Bill Gates bump.

Just before Christmas, he learnt that his book had been favourably reviewed by Mr Gates on his blog, Gates Notes.

"I'm surprised by the number of biographies I read that paint their subjects in black-and-white terms," Mr Gates wrote.

"A classic example is former US president Richard Nixon, who is too often portrayed as little more than a crook and a warmonger. So it was refreshing to see a more balanced account in Being Nixon, by author and journalist Evan Thomas."

The review was illustrated by a photograph of the book on a desk adorned with objects from the Nixon era, like a rotary phone.

Thomas was taken by surprise. "I've never met Bill Gates," he said. "I had no idea he had a books blog."

"I was thrilled because he has a lot of reach," he said, adding that sales of the book jumped soon after that review was posted.

"I can tell the blog is well read because I heard from all sorts of random people."

For years, Mr Gates, the co-founder of Microsoft who now focuses on the philanthropic work of the Bill & Melinda Gates Foundation, had been scribbling notes in the margins of books he was reading and then e-mailing recommendations to friends and colleagues.

Then he began to post these recommendations and critiques on the blog.

"A few years ago, I started thinking it would be fun to share some of these notes with the public," he wrote in a recent e-mail interview.

"I have always loved reading and learning, so it is great if people see a book review and feel encouraged to read and share what they think online or with their friends."

He says he reads about 50 books a year, eschewing digital readers for old-fashioned books on paper. When he is busy with work, he reads about a book or two a week, but will consume four or five in the same period while vacationing with family.

He has loved reading since boyhood.

"I did things like reading the encyclopaedia for fun," he said, "and I was lucky in that my parents would buy me any book I wanted."

The books section is one of a handful on his blog. He also writes on his philanthropic work and his foundation's endeavours in healthcare, education and the like.

The blog is filled with personal touches like a slideshow of him with his friend Warren Buffett (including one of Mr Buffett doing push-ups at Mr Gates' 50th birthday celebration) and an ode to his father to mark his father's 90th birthday.

But his book reviews tend to generate the most attention.

On Gates Notes, he often recommends books that have a bend towards science and public health. This year, he read, and liked, Stuff Matters: Exploring The Marvelous Materials That Shape Our Man-Made World, by Mark Miodownik; On Immunity: An Inoculation, by Eula Biss; and Should We Eat Meat? Evolution And Consequences Of Modern Carnivory, by Vaclav Smil, to name a few.

Last month, he published a short list and accompanying video of his favourite books read last year. (His reviews are not necessarily for books published within the calendar year.)

The list included Thomas' Nixon biography; Eradication: Ridding The World Of Diseases Forever? by Nancy Leys Stepan; and Mindset: The New Psychology Of Success, by Carol S. Dweck. ("Mindset first came to my attention a few years ago," Mr Gates wrote, "in a fascinating invention session on education with my friend Nathan Myhrvold.") On the best-of list, he also included Thing Explainer: Complicated Stuff In Simple Words, by Randall Munroe, the graphic writer and cartoonist who created the blog XKCD.

Earlier in the year, he lavished praise on an earlier book of Munroe's: What If? Serious Scientific Answers To Absurd Hypothetical Questions.

"My guess is that you haven't spent a whole lot of time wondering what would happen if you pitched a baseball at 90 per cent of the speed of light," he wrote.

"I haven't either. But that's OK, because Randall Munroe has figured it out and explained it really clearly in his book What If?"

Munroe first learnt that Mr Gates had read and enjoyed his book when a relative sent him a screen shot of a photograph showing Mr Gates reading his book.

"I stared at it for a while," Munroe said in a phone interview. "It didn't really register. I didn't know what to do."

Mr Gates said in the interview that he tries to fill his reviews with bits of information he hopes people will consider, even if they do not end up reading the book.

"I read textbooks related to global health but they are pretty technical for a general audience, so I generally don't review them," he said.

"I make an exception for things like Sustainable Materials: With Both Eyes Open, where the authors' conclusions are important and they help clarify some important basic facts. I like to share what I learn from books like that because I know most people won't read the whole thing, but some will read an 800-word review of it."

He also shares some unexpected titles. Of Allie Brosh's memoir, Hyperbole And A Half: Unfortunate Situations, Flawed Coping Mechanisms, Mayhem, And Other Things That Happened, Mr Gates wrote: "You will rip through it in three hours, tops. But you'll wish it went on longer, because it's funny and smart as hell. I must have interrupted Melinda a dozen times to read to her passages that made me laugh out loud."

Of the novel The Rosie Project, by Graeme Simsion, Mr Gates wrote: "I started it myself at 11pm one Saturday and stayed up with it until three the next morning. Anyone who occasionally gets overly logical will identify with the hero, a genetics professor with Asperger's syndrome who goes looking for a wife. (Melinda thought I would appreciate the parts where he's a little too obsessed with optimising his schedule. She was right.)"

He rarely posts negative reviews of books, explaining that he sees no need to waste anyone's time telling them why they should not bother reading something. He does not spare himself, though.

"I have a habit, which I don't recommend, of finishing essentially every book I start," he said. "And if I disagree with a book, I spend lots of time writing notes in the margins. Perversely, this means that the more I dislike a book, the longer I spend reading it."

As publishers have become more aware of Mr Gates' reviews - missing the publicity they used to get from Oprah Winfrey's televised book club or from the regular author appearances on The Colbert Report, which have been less frequent since Stephen Colbert moved to CBS from Comedy Central - they have tried to figure out how to get their new books in front of Mr Gates.

Ms Stephanie Kim, a publicist for Munroe's publisher, hustled her way into a connection with someone on Mr Gates' team only to be told, "We don't have any say over what Bill chooses. We just leave it on his desk and he reads what he wants to read".

Ms Kim lucked out.

Mr Gates' reading selections are influenced by his wife, his work and the experiences that move him.

"Someone at the foundation recently recommended The Vital Question, by Nick Lane," he said, "which is about mitochondria and the origins of life on Earth. It was so good that as soon as I finished it, I ordered all of Lane's other books."

"This is one of the things I love about reading," he said. "Each book opens up new avenues of knowledge to explore."

NEW YORK TIMES