Captain Abbott, who was generally accredited with possessing several pairs of eyes, noted that Mr.Prescott had halted.
For some moments the young man went anxiously over what he had already written.

At last he turned around, facing the instructor, and saluted.
"Permission to erase, sir ?" requested Prescott., Captain Abbott nodded his assent.
Picking up the eraser, Dick carefully erased the last two lines that he had set down.
Then, as though working under a new inspiration, he went ahead setting down line after line of the demonstration of this difficult problem.

Only once did he halt, and then for not more than thirty seconds.
Dunstan went through a halting explanation of his problem.

Then Captain Abbott called: "Mr.Prescott!" Taking up the short pointer, Dick rattled off the statement of the problem.

Then he plunged into his demonstration, becoming more and more confident as he progressed.
When he had finished Captain Abbott asked three or four questions.
Dick answered these without hesitation.
"Excellent," nodded the gratified instructor.