t is the custom of many companies to require their
conductors to take down immediately the names of a few of the most
respectable-looking of the passengers, who may be called as witnesses in
case of a lawsuit. All the observations of science, and most of the
facts brought before juries in courts of law, as well as the multitude
of lesser and greater facts which we accept in everyday life, get their
authority from this principle.

In the arguments of school and college you may not make much use of
direct evidence, for they do not often turn on single, simple facts.
Even here, however, cases arise where you must call in the direct
testimony of witnesses. If you were arguing that secret societies should
be abolished in a certain school, and wished to show that such societies
had led to late hours, playing cards for money, and drinking, you would
need direct evidence. If you were arguing that the street railroad
company of your city should be obliged to double track a certain part of
its line, you would need direct evidence of the delays and crowding of
cars with a single track.

When you are using direct evidence you should make it clear that the
person from whom it comes is a competent witness, that he has been in a
position to know the facts at first hand, and that, if necessary, he has
had the proper training to understand their meaning. In the case of an
automobile accident a man who had never run a car would not be the best
sort of witness as to the actions of the chauffeur, nor a man who had
never sailed a boat as to what happened in a collision between two
sailboats. In a scientific matter the observations of a beginner would
not carry weight as against those of a man who had used a microscope for
many years.

The witness, too, must be shown to be free from bias, whether practical
or theoretical. It is a well-known fact that men differ greatly in the
clearness of their eyesight in observing the stars, and that men who are
gifted with exceptional eyesight may make valuable discoveries with
inferior instruments; but if such a man has espoused a theory, say, as
to the nature of the rings of Saturn, and is known to defend it
passionately, his evidence concerning what he had seen is bound to be
somewhat discounted.

Even official reports cannot be trusted without scrutiny.

The fact is that many things conspire to make an official report
constrained and formal. There is the natural desire of every man to put
the be