Maren Sophie Samuelsdatter and Martinius Samuelson

They were brother and sister who left Modum on the SS Argo in 1869, bound for Prairie du Chien, Wisconsin via Hull. I am looking for the connecting ship from Hull/Liverpool to America. Maren took the name Mary in America. I can trace her to Minneapolis, but not Martinius. Any US information on him would be very helpful, too. Thanks!