It was during this melee that Slim spied the searchlight of the launch and let out his first call. After that most of his "bellows" were involuntary and but punctuated the rapid-fire attack with which the other man was landing his blows just above Slim's waist-line, or where his waist-line should have been. As the launch headed toward shore, its searchlight trained over the bow, the man of the rowboat resorted to more desperate tactics. With a tremendous jerk he managed to free his throat from Slim's grasp. An instant later he gave the youth's neck a twist which almost broke it. Then he landed a vicious kick which put poor Slim out of business. Just as the marines from the launch were climbing ashore the fellow sped off into the denseness of the night; and as his footsteps died away all present trace of him was gone. A dozen of them searched for an hour, but without result, and further investigation along that line had to be abandoned until the following day. Meanwhile, however, all three lads were hurried back to the navy yard for fresh clothing and other repairs; having received which, together with hot coffee from the cook at the barracks mess, they were permitted, at their own earnest solicitation, to return to the scene with four marines who were to be stationed along that section of the shore for the balance of the night. What they saw upon their arrival astounded them. Three additional launches had arrived upon the scene, and the commandant of the navy yard was himself directing matters. He had in his hand a slight rope that ran down into the water, and close beside it was a hose line attached to an apparatus in the boat. The boys knew at once that a diver was at work down on the river bed. From the side of another launch anchored parallel with the first, and fifteen feet distant, four husky bluejackets were waiting expectantly to divide their strength on two stout ropes that were being attached to something down in the water. The third launch played its flashlight upon the work, while the fourth steamed about, doing patrol duty. Even as the boys watched, the commandant gave a signal and the sailors began hauling upward on the two heavy ropes. In a moment an oblong box, about two feet long, a foot wide and of the same depth, came dripping from the water. As it was brought to the boat's side two other men grasped it carefully and placed it in the bottom of the launch. Then the ropes, which were attached to a guide line, were hauled down into the river again. "What does it mean?" Joe asked of Sergeant Martin, who had changed his clothes and arrived back ahead of them. "What does it mean?" repeated the big sergeant. "It means that you three young men are due for several credits and early recognition, or I'm much mistaken. The man you discovered has not yet been caught, but he cannot escape for long. And when he is captured it will be a long time before he is free again.