Our guest on ST is Harold McGee, who writes about the science of food and cooking. His earlier books include "On Food and Cooking: The Science and Lore of the Kitchen" and "Keys to Good Cooking: A Guide to Making the Best of Foods and Recipes." He joins us to discuss his new book, "Nose Dive: A Field Guide to the World's Smells." As was noted of this work by Booklist: "In his detailed survey of scents, food writer and cooking scientist McGee elegantly explains olfaction.... His exploration of our smelly world includes the odors of flora and fauna, soil and smoke, food and fragrances, but also the unexpected: primordial earth, rain, and the whiff of old books. Pungent and even rancid smells -- skunk spray, ammonia, manure -- are as respected as such delectable aromas as lemon, coffee, and rosemary. Odiferous facts abound.... A delightful outing across the olfactory world."