“That’s it. There’s another battleship gone,” cried Tom, as we all hurried over to the scale. “Now we can tell just where he is doing his deadly work. 2, 340, 624. 1401” he read, scrutinizing with a microscope the scale at the point where the beam rested. “Here, Jones, turn on the lights. Bring me the logarithm tables, our table of constants, and Denckel’s table of constants that we found under the middle cylinder.” Jones ran excitedly across the laboratory, returning with the needed things. Tom, Dorothy and Jones each sat down to figure while I watched Dorothy’s nimble fingers, as they flew over the paper, filling sheet after sheet with computations. What different powers lay in those little hands. Abstruse calculations vied with bread making, careful manipulations of delicate instruments with the steering wheel of her motor car. Last week we had eaten a dinner prepared wholly by her. This week she was working out one of the great triumphs of modern science. It seemed almost a shame to confine those talents in a single home--but yet--and the old train of thought started on its ever recurring cycle. Suddenly Tom threw down his pen. “Beat you that time, old girl!” he said. Dorothy gave no heed, but figured on for a minute more. Then she, too, dropped her pen. “Want my figures, Tom?” she asked. “Not yet,” answered Tom. “Wait for Jones. I’ll go and get the maps, and we’ll work the second step as soon as we have checked these figures.” Jones worked laboriously on, and Tom had gone and returned, bearing two huge portfolios, before his task was ended. “Read off,” said Tom, and a whole series of numerals came from Dorothy’s lips, at each of which Jones nodded his head. As she ended she looked inquiringly at Tom. “Right,” said he. “Now reverse the beam to find the slit.” Jones brought a small scale, with lights mounted with flexible cords. He placed it across the beam, sighted through it as Tom threw off the lights, and, after a brief manipulation, threw a switch. All turned to gaze at the belt. Through a single slit an almost geometric line of light shone forth. “Beautiful! beautiful!” cried Tom; and Dorothy cried, “Oh, Jim! oh, Tom! we’ve got it.” My name came first to her hour of triumph. I had time to notice that, before the lights went on once more. Tom took a dozen hasty readings, and rapidly read them off. Another period of rapid computation followed, then one by one, Dorothy leading, they made a swift survey of maps. More and more anxious grew the trio as they went on. Map followed map, till Dorothy came to a final one, made her last measurement, and sat back in apparently complete bewilderment. Tom, by a different route, reached the same map and drew it from her, shaking his head vehemently, and Jones, laboring heavily along in the rear, finally stretched his hand for the same sheet. “What have you got, Jones?” said Tom sharply. “Tokio, Japan,” said Jones. “What do you get?” “Tokio, confound it!” said Tom.