e determined, and it registered 102
degrees. It might be that Harry's temperature was really much higher, as
the thermometer, for the reasons stated, was not accurate.

"I wish you would test the thermometer, George, so we can pretty well
determine, within a range of two or three degrees, how nearly right we
are."

George's temperature was found to register 98, whereas the Professor's
was only 90. He explained that the temperature of youth is normally
greater than old age, but it was remarkably close to the average normal
temperature of two healthy persons.

"The advantage of the instrument now is to enable us to ascertain
whether Harry's temperature will increase or decrease."

"Is there no other way in which we can find out about a fever?"

"When the fever comes on the pulse is usually quickened, as well as the
breathing; the bowels are apt to be constipated; and thirst, loss of
appetite, headache, and vague pains are felt. When the temperature goes
beyond 105 it is very dangerous, and it is for this reason that
physicians want to know the temperature."

"I am anxious to know why that C-shaped piece should try to straighten
itself out when heat is applied to it?"

"When you bent the metal piece of which it is made you crowded the metal
on the inside of the piece together, and also stretched the metal on the
outside of the bend. As the application of heat expands the metal, the
contracted particles of the metal on the inside of the piece pushed
against each other with greater force than those on the outside, and the
bar tried to straighten itself out again."

"I have noticed that if a hose is coiled up and water is forced through
under pressure it will straighten out the hose. Is that also the case
with the hose?"

"To a certain extent only. Another principle comes into play in that
case. Water under pressure acts as a solid, and has a tendency to move
along the shortest route or in the most direct way. If, therefore, there
is a crook in the pipe the water tries to straighten it out. Steam
gauges are made of flattened spirally coiled tubes. One end of the tube
is open and the other has an inlet for the steam. The dial finger has a
connection with the moving end, and by that means pressure is
indicated."

The next morning Harry's temperature was fully one degree higher than
the previous day, and the Professor advised that it would be necessary
to administer some fever medicine.

"Last week you found severa