once more. The younger examiner showed remarkable tact in feeling his way, and keeping within the very limited area of the student's knowledge. He succeeded so well, however, that although his colleague shook his hoary head and intimated in other ways his poor opinion of the candidate's acquirements, he was forced to put down another "S. B." upon the paper in front of him. The student drew a long breath when he saw it, and marched across to the other table with a mixture of trepidation and confidence, like a jockey riding at the last and highest hurdle in a steeple-chase.
Alas! it is the last hurdle which often floors the rider, and Thomas too was doomed to find the final ordeal an insurmountable one. As he crossed the room some evil chance made him think of the gossip outside and of his allusion to the abstruse substance known as cacodyl. Once let a candidate's mind hit upon such an idea as this, and nothing will ever get it out of his thoughts. Tom felt his head buzz round, and he passed his hand over his forehead and through his curly yellow hair to steady himself. He felt a frenzied impulse as he sat down to inform the examiners that he knew very well what they were going to ask him, and that it was hopeless for him to attempt to answer it.
The leading professor was a ruddy-faced, benevolent old gentleman, with spectacles and a kindly manner. He made a few commonplace remarks to his colleagues with the good-natured intention of giving the confused-looking student before him time to compose himself. Then, turning blandly towards him, he said in the mildest of tones—
"Have you ever rowed in a pond?"
Tom acknowledged that he had.
"Perhaps, on those occasions," the examiner continued, "you may have chanced to touch the mud at the bottom with your oar."
Tom agreed that it was possible.
"In that case you may have observed that a large bubble, or a succession of them has risen from the bottom to the surface. Now, of what gas was that bubble composed?"
