Before revision: We present a routing algorithm for the Theta-4-graph  that computes a path between any two vertices s and t having length at most 17 times the Euclidean distance between s and t.
After revision: We present a routing algorithm for the Theta-4-graph -graph, that computes a path between any two vertices s and t having length at most 17 times the Euclidean distance between s and t.