The time trippers go west

The book is about two friends,Matt and Linda. They usually travel in time whit Mr.Wells's help. One day, Mr.Wells doesn't appear in the school, and nobody knows anything about him, except Matt and Linda, they are sure he's lost in time, but they don't know where is him, so at the end of the day they go to Linda's house, and when Linda switch on her computer an animated picture of Mr.Wells appears in it. The Picture could talk and said to them that he is in North america in 1862, in the American civil war. They travelled in the time,but they traveled to a wrong place and then they made a long journey. Like all the books about the time trippers, they learned a lot about American civil war and indians.