"The force is attraction toward all matter, generated by the vibrations of all the constituent electrons in parallel planes. It is directed along a line perpendicular to the plane of vibration at its center, and approaches infinity as the angle theta approaches the limit of Pi divided by two. Therefore, by shifting the axis of rotation or the plane of vibration thus making theta vary between the limits of zero and Pi divided by two...." He was interrupted by Dorothy, who, mortified by her thoughtlessness in getting him started, had sprung up and seized him by the arm. "Sit down, Dicky!" she implored. "Sit down, you're rocking the boat! Save your mathematics for Martin. Don't you know that I could never find out why 'x' was equal to 'y' or to anything else in algebra?" She led him back to his chair, where he drew her down to a seat on the arm beside him. "Whom do you love?" she whispered gayly in his ear. After a time she freed herself. * * * * * "I haven't practised today. Don't you want me to play for you a little?" "Fine business, Dottie. When you play a violin, it talks." She took down her violin and played; first his favorites, crashing selections from operas and solos by the great masters, abounding in harmonies on two strings. Then she changed to reveries and soft, plaintive melodies. Seaton listened with profound enjoyment. Under the spell of the music he relaxed, pushed out the footrest of the chair, and lay back at ease, smoking dreamily. The cigar finished and his hands at rest, his eyes closed of themselves. The music, now a crooning lullaby, grew softer and slower, until his deep and regular breathing showed that he was sound asleep. She stopped playing and sat watching him intently, her violin in readiness to play again, if he should show the least sign of waking, but there was no such sign. Freed from the tyranny of the mighty brain which had been driving it so unmercifully, his body was making up for many hours of lost sleep. Assured that he was really asleep, Dorothy tip-toed to her father's study and quietly went in. "Daddy, Dick is asleep out there in the chair. What shall we do with him?" "Good work, Dottie Dimple. I heard you playing him to sleep--you almost put me to sleep as well. I'll get a blanket and we'll put him to bed right where he is." "Dear old Dad," she said softly, sitting on the arm of his chair and rubbing her cheek against his. "You always did understand, didn't you?"