Technology evangelists have predicted the emergence of electronic books for as long as they have envisioned flying cars and video phones. It is an idea that has never caught on with mainstream book buyers. Two new offerings this fall are set to test whether consumers really want to replace a technology that has reliably served humankind for hundreds of years: the paper book.In October, online retailer Amazon.com will unveil the Kindle, an electronic book reader that has been the subject of industry speculation for a year, according to several people who have tried the device and are familiar with Amazon’s plans. The Kindle will be priced at $400 to $500 and will wirelessly connect to an e-book store on Amazon’s site. That is a significant advance over older e-book devices, which must be connected to a computer to download books or articles.Also this fall, Google plans to start charging users for full online access to the digital copies of some books in its database, according to people with knowledge of its plans. Publishers will set the prices for their own books and share the revenue with Google. So far, Google has made only limited excerpts of copyrighted books available to its users. These new services, from two Internet heavyweights, may help to answer the question of whether consumers are ready to read books on digital screens instead of on processed wood pulp. Hopes for e-books began to revive last year with the introduction of the widely marketed Sony Reader. Sony’s $300 gadget, the size of a trade paperback, has a six-inch screen, enough memory to hold 80 books and a battery that lasts for 7,500 page turns. It uses screen display technology from E Ink, a company based in Cambridge, Mass, that emerged from the Media Lab at the Massachusetts Institute of Technology and creates power-efficient digital screens that uncannily mimic the appearance of paper. Sony will not say how many it has sold, but the Reader has apparently done well enough that Sony recently increased its advertising for the device in several major American cities. “Digital readers are not a replacement for a print book; they are a replacement for a stack of print books,” said Ron Hawkins, vice-president for portable reader systems at Sony. “That is where we see people, on the go, in the subway and in airports, with our device.” Book publishers also seem to be preparing for the kind of disruption that hit the music business when Apple introduced the symbiotic combination of the iPod and its iTunes online service. This year, with Sony’s Reader drawing some attention and Amazon’s imminent e-book device on their radar, most major publishers have accelerated the conversion of their titles into electronic formats. “There has been an awful lot of energy around e-books in the last six to 12 months, and we are now making a lot more titles available,” said Matt Shatz, vice-president for digital at Random House, which plans to have around 6,500 e-books available by 2008. It has had about 3,500 available for the last few years.Many say this is where the device’s real innovation lies — in its ability to download books and periodicals, and browse the Web, without connecting to a computer. The device has a keyboard, so its users can take notes when reading or navigate the Web to look something up. A scroll wheel and progress indicator next to the main screen, will help users navigate Web pages and texts on the device.