TO ALL THOSE WHO LEAD MONOTONOUS LIVES IN THE HOPE THAT THEY MAY EXPERIENCE AT SECOND HAND THE DELIGHTS AND DANGERS OF ADVENTURE   PROLOGUE It was 2 p.m. on the afternoon of May 7, 1915. The Lusitania had been struck by two torpedoes in succession and was sinking rapidly, while the boats were being launched with all possible speed. The women and children were being lined up awaiting their turn. Some still clung desperately to husbands and fathers; others clutched their children closely to their breasts. One girl stood alone, slightly apart from the rest. She was quite young,