plied to rather lamely. Even
more as a matter of getting back at this young investigator who sat with
a crutch held before him and regarded these replies with a smile than
for the desire to measure minds, Davidson gathered a few catch problems
that were stumpers, and upon his third visit, after talking awhile he
switched off on the subject of problems, short cuts to solutions and
then put a question, looking hard at Bill, as though uttering a
challenge.

"Now, how would you go about it," he shot at his audience, "if you were
asked to measure the cubic contents of an electric light bulb?"

A number of smiles greeted the question; these may have been from lads
mostly in the advanced courses who knew the trick. The lecturer asked
for hands to be raised by those who thought they could do it, and noting
with satisfaction that the crippled boy was not among the number who
responded, he began hearing them, one at a time.

"Measure it outside and allow for the thickness of the glass," said one
fellow.

"But how about the carbon inside?" asked Davidson.

"Break the glass and measure the loop," called out a soph.

"How many of you would go at it in that way?"

A number of hands went up, some rather reluctantly, as though their
owners scented a trick.

Davidson still eyed the cripple. "How would you do it?" he asked.

Bill shook his head and said, "It is that old trick of Edison's and it's
dead easy. I guess a good many of our fellows know about it. You simply
punch a hole in the bulb, fill it with water, pour it back and measure
the water."

"Yes; that's right. It is really the only sure way," said the man, his
manner showing disappointment.

"Oh, no; it isn't, begging your pardon. Oh, no, not the only way," said
Bill.

"Well, now, how else----"

"Put water in a graduated glass, stick the bulb in up to the plaster
seal and note the increase. Then break the glass and the carbon and put
that in separately, deducting the last amount from the first."

Davidson scratched his head. "Yes; that would do it, of course, too,
but----"

"But you said the other was the only way," insisted Bill.

"Oh, well, the only quick and sure way. Of course, there are other
methods."

"I'm sorry to have to disagree with you, but my method is just as sure
and quicker."

"It might do--it might do! You seem to be ready with short cuts in
mechanics. How would you quickly divide a board seventeen and
three-eighths inches wide into five