If you want to know where you are, you need a good clock. The surprising connection between time and placeais explored inaTime and Navigation- The Untold Story of Getting from Here to There, the companion book to the National Air and Space Museum exhibition of the same name. Today we use smartphones and GPS, but navigating has not always been so easy. The oldest "clock" is Earth itself, and the oldest means of keeping time came from observing changes in the sky. Early mariners like the Vikings accomplished amazing feats of navigation without using clocks at all. Pioneering seafarers in the Age of Exploration used dead reckoning and celestial navigation; later innovations such as sextants and marine chronometers honed these techniques by measuring latitude and longitude. When explorers turned their sights to the skies, they built on what had been learned at sea. For example, Charles Lindbergh used a bubble sextant on his record-breaking flights. World War II led to the development of new flight technologies, notably radio navigation, since celestial navigation was not suited for all-weather military operations. These forms of navigation were extended and enhanced when explorers began guiding spacecraft into space and across the solar system. Astronauts combined celestial navigation technology with radio transmissions. The development of the atomic clock revolutionized space flight because it could measure billionths of a second, thereby allowing mission teams to navigate more accurately. Scientists and engineers applied these technologies to navigation on earth to develop space-based time and navigation services such as GPS that is used every day by people from all walks of life. While the history of navigation is one of constant change and innovation, it is also one of remarkable continuity. Time and Navigation tells the story of navigation to help us understand where we have been and how we got there so that we can understand where we are going.

Whether out for an afternoon's sail or embarking on a long offshore passage, there is always an element of chance and uncertainty about being at sea. To be responsible for the wellbeing of both crew and vessel, a good skipper needs to know their limitations and ensure they are operating well within the margins of safety. Safe Skipper is a practical and thought provoking guide for yacht skippers of all levels of experience, full of invaluable advice and tips on how to reduce to the minimum the risks of mishaps and equipment failure at sea. There's a wide range of information on seamanship, preparation, seaworthiness, gear, boat handling, leadership, teamwork, watch keeping, communications, navigation, weather and emergency procedures, all delivered in a highly practical, lively, non-preachy fashion. Included throughout are useful checklists, box-outs and case studies of accidents and their causes, with survivors' testimonials and explanations of how disasters were avoided, or could have been, all of which provides valuable lessons for everyone who goes to sea.

Through the concept of "social navigation," this book sheds light on the mobilization of urban youth in West Africa. Social navigation offers a perspective on praxis in situations of conflict and turmoil. It provides insights into the interplay between objective structures and subjective agency, thus enabling us to make sense of the opportunistic, sometimes fatalistic and tactical ways in which young people struggle to expand the horizons of possibility in a world of conflict, turmoil and diminishing resources.