Amazon in a rare evening launch revealed its third-generation Kindle reader. The new hardware is 21 percent smaller and 15 percent lighter than the model it replaces but is better in nearly every way. It uses a new E Ink Pearl display with 50 percent better contrast and 20 percent faster page turns but can now last for up to a month with wireless off on battery, twice as much as before, and for up to 10 days with wireless on.