"In the same manner... when the air contiguous to a fire is heated... it is immediately expanded very much; and therefore instantly rises upwards, till it reaches the higher regions of the atmosphere, or is cooled by gradually mixing with the denser air it meets with in its ascent:—and as its place contiguous to the fire is immediately occupied by the cold dense air around it, which rushes from every side towards that point, it is heated and rarefied in its turn, and ascends in the same manner, carrying the smoke that rises from the burning body along with it."