In the eternal quest for a cleaner, brighter, better cup, coffee mavens have utilized French presses, Clover machines, and drip bars. The new Third Rail Coffee, a cubbyhole café near NYU, takes a fresh approach: filtering its single-origin Intelligentsia roasts directly into Chemex flasks. Other things you’ll find there include bench seating, Ceci-Cela pastries, cold-brewed iced coffee, and a sunny and serious staff, headed by barista-about-town Dan Griffin, late of Williamsburg’s Variety and El Beit (240 Sullivan St., nr. W. 3rd St.; no phone).