'...With that impressionistic gallop through history as a backdrop, let me touch upon some of the technical material that has come to light as a result of urban fires and the research devoted to their prevention and cure. Perhaps the dominant area of uncertainty and of study effort has been and continues to be the development and spread of fire. Spread machanisms are three in number: convection, radiation and firebrands. Everyone who has lived in a home or cabin with a space heater has benefitted from convection, that tangible flow of hot air , rising from the top of a space heater. For the student of fire, this comes to the fore in several cases. First, there is a problem of how a room heats up and progresses from a small fire involving say one piece of furniture to a full-room 'flashover,' a phenomenon well known to fire fighters the world over. Accounts of the Chicago fire, and the New York City fire of 1835 emphasize the 'explosion into flames' of entire buildings, originally considered 'fireproof.'...'