John Christopher 
New Found Land 

Traveling through time was just the beginningnow Simon and Brad have to survive a reimagined early America in the second book of the alternative history Fireball trilogy, from critically acclaimed Tripods author John Christopher.When Simon and Brad were caught in the mysterious fireball and transported to the strange alternate world on the other side, they knew their lives would never be the same again. They definitely couldnt have imagined the dangers ahead, especially when they set sail for Brads homeland: the still undiscovered America. The Algonquian territory is hardly the paradise Brad had been promisedor remembered from history class. Winter is brutal, the locals are hostile, and Simon and Brad know they have to escape. But can they? The adventures in storefrom Vikings to a completely unexpected civilizationput their will to survive to the ultimate test.