"Well, let's hope your genius will pull off the Richoter for you," put in Kitty. "Then Carslake's can crow for once in its life. There's the dinner bell. You'll see our Richoter candidate doesn't faint this afternoon through lack of nourishment, won't you, France?" By two o'clock that afternoon the four houses were quiet and deserted, all except the Richoter candidates being in their classrooms. Little did they dream, as the clock hand pointed to the half hour and then crept onwards, of the drama that was being enacted even then in the science laboratory. The nine candidates had assembled punctually at two-thirty; Duane had handed over the key to Miss Vacher and, Miss St. Leger also with them, they had entered the room and taken up their former places to continue their work. There was several minutes' silence while the girls began to take their compounds from the midget furnaces, preparatory to weighing. Miss St. Leger and Miss Vacher were talking together in low tones when a sudden exclamation from Salome made them glance up quickly. With an expression of amazement on her face the girl was gazing at one of the pans which she had just removed from her balance; underneath the pan was a small gravel pebble attached to the pan by means of a piece of plasticine. She swung round quickly as the Principal's voice, from just behind her, said sharply: "Has someone been interfering with your balances, Constance?" (Constance was Salome's baptismal name.) [Illustration: "'Has someone been interfering with your balances, Constance?' asked the Principal."] "It--it seems so, Miss St. Leger," stammered Salome. "I tested my balances to see if they were correct before weighing, and was astonished to find one side much heavier than the other. Then I took off the pans to try and find the cause and discovered this piece of gravel underneath one of them." The faces of the Principal and the science mistress were very grave, for it looked as if a deliberate attempt had been made to spoil Salome's results. Aware that the other girls in the room had paused in their work to listen in astonishment, Miss St. Leger said decidedly, "Continue your work, girls. Constance, I will inquire into this as soon as you have all finished your practical work. Go on now with your experiment." The Principal stayed in the room till the time allotted for the practical work was over, then she called them all together round the bench where Salome, Eileen and Duane had been working and explained to them exactly what had happened. They looked at one another with mingled feelings of discomfort and amazement. Miss St. Leger first questioned Salome. "When did you use your balances last--I mean before your discovery at the beginning of the afternoon?" "This morning," replied Salome at once. "Not long before we left. We had to weigh our compounds before putting them into the midget furnaces to heat during the dinner hour." "You are sure they were correct then?"