_ cnsunnmz v. THOMPSON. 39
error to the supreme court, to review the actions and rulings of this court,
a regular bill of exceptions was unnecessary, and is not strictly essential,
on a motion for a new trial, as the recollections of the court may be aided
by aiiidavits and the briefs of counsel. Written and signed exceptions
would be of service on this motion, as the counsel of the parties do not,
in some respects, concur in their recollections of the proceedings, and the
court does not clearly and distinctly remember all the details of the trial.
I have a strong impression as to the decided preponderance of the tes-
timony in favor of the plaintiffs, and the justness of the verdict.
As the counsel of defendants, in their arguments and elaborate brief,
have manifested such earnest confidence in the correctness of their legal `
propositions, I have considered their motion with some degree of care,
upon their statement of exceptions taken on the trial. I have not
deemed it necessary to refer tothe statements of the recollection of the
counsel of the plaintiiis, and decide questions of variance in the matters
in dispute.
Before referring specially to the arguments and the authorities cited
by the counsel of the parties, I will state some general principles of law
involved in the controversy, as announced by text writers and sustained
by decided cases. Where atwitness is oiiered as an expert, fortthe pur-
pose of giving information and opinions to the jury to aid them in their
determination of questions of fact, the court, by means of a preliminary V
examination, must Hrst determine, as a question of fact, the qualilica-
tions of the witness as an expert. The proper test for the admissibility
of such testimony is whether the witness offered as an expert has any
peculiar knowledge or experience, not common to mankind, which renders
his opinions founded on such knowledge or experience any aid to the
court or jury in correctly determining the questions at issue. When
such witness is adjudged to be an expert, he may be allowed to testify ·
on questions of science or skill in any art or trade in which he is in-
structed by study or experience. Every business or employment requir-
. ing peculiar knowledge or experience, and which has a particular class of g
persons devoted to its pursuit, is an art or trade; and any person who, by
study or experience, has acquired this peculiar knowledge and practical
skill, may be allowed to give in evidence his opinions upon such matters
of technical knowledge and skill, within the limits of his business, to
enlighten the minds of a jury where they have to determine such mat-
tersin a pending trial. An expert cannot be properly allowed to ex-
press an opinion, on the whole evidence, as to the general merits of a
case, or as to the amount of damages that ought to be assessed in a trial,
as these are questions exclusively for a jury to determine.
'When an expert may properly express an opinion, he does not decide
the questions in issue; he only aids the jury in arriving at correct con-
clusions, and they must determine the questions of fact about which the
opinion of the expert was given. The credibility of such testimony
may be tested by the rules of evidence applicable to other witnesses, and
its value greatly depends upon the knowledge, experience, opportunity,
and capacity of the witness, and the soundness of the reasons upon