tions before allowing him to give his opinion, and it is the general practice for the opposing party to exercise his privilege of cross-examination on the matter of qualifications after the witness has been examined in full by the party offering him. That is the more convenient practice. And in Finch vs. Chicago, etc., R. Co., 46 Minn., 250, the court said: "We think it is the understanding of the judges and the bar that while the court may, in its discretion, permit a preliminary cross-examination, it is not bound to do so, but may allow the opinion to be given when the direct examination shows prima facie that the witness is qualified."

SECTION 46. SUBJECTS OF EXPERT INQUIRY.

The following have been held proper subjects for the introduction of expert testimony: The care and handling of domestic animals; meaning of entries in books; agriculture and crops; diseases of men or of animals; blood and blood-stains; the nature and effects of poisons; architecture and building; chemistry; all branches of medicine and surgery; anatomy; electricity; explosives and fire-arms; jewelry; engineering and machinery; cause of death; abortion; drowning; suffocation; strangulation; time of death; post-mortem examinations; genuine and feigned diseases; pregnancy; rape; nature, cause and effect of wounds, and the means by which probably inflicted; distance at which shot was fired; whether wounds were suicidal or homicidal; seaworthiness of vessels and seamanship; medical remedies and appliances; surveying; photography; weather; law of a foreign state; gas and steam fitting; geology; elevator devices; midwifery; botany; banking; insanity; malpractice, injuries and wounds, etc.

SECTION 47. HYPOTHETICAL QUESTIONS.

The proper practice in examining an expert witness where his opinion is sought, is to propound to him a hypothetical question, assuming as true certain facts which comport with and seem to sustain such party's theory of the case, and which the evidence tends to prove, and which facts should be stated in the hypothetical question. The witness then gives his opinion thereon, providing such facts so stated are sufficient upon which to base an intelligent opinion of some probative weight and value to the jury. It is not necessary to include all the facts, disputed and undisputed, which the evidence tends to prove, in the hypothetical question, but it should properly include all facts essential to some theory of the case.

Counsel objecting to a hypothetical question should point out specifically what admitted fact he claims to have been improperly omitted, so that, if the court holds the objection good, the propounder of the question may amend the same. A general objection will not avail. It would seem, however, that all material undisputed facts bearing upon the matter concerning which the opinion of the witness is sought should be included in the hypothetical question. However, the later decisions seem to hold that if opposing counsel think any material fact or facts should be included in the hypothesis, he has a right, on cross-examination, to take the opinion of the witness upon his version of the testimony with such fact or facts included.2

SECTION 48. OPINIONS OF NON-EXPERTS.

A non-expert may, after testifying fully as to his opportunities and means of knowledge, give his opinion ⚫ Riverton Coal Co. vs. Shepherd, 207 Ill., 398.

on the following subjects: The sanity or apparent health of a person by him observed; speed of railway trains and street cars; within what space they could be stopped; condition of tracks and ties; age of a person; the identification of persons, animals, or things; intoxication of an individual; heat; cold; light; darkness; shape; size; distance; quantity; time and duration; force of a sudden jerk of a car; conduct and demeanor of a person not easily described; value of his own services, and of articles in common use.

A subscribing witness may give his opinion as to whether the testator at the time he made his last will and testament was of sound and disposing mind and memory.

SECTION 49. MEDICAL AND SCIENTIFIC BOOKS.

The weight of authority seems to sustain the doctrine that medical and scientific books, even though they be standard authorities on the subjects to which they relate, including the U. S. Pharmacopoea, are not admissible in evidence, although the decisions in the various jurisdictions are not uniform. Books of science by statute in some states have been made competent evidence.

Where, however, an expert has testified that he based his opinion upon a certain medical or scientific book, such book may be read in evidence to contradict his opinion.

SECTION 50. PHOTOGRAPHS AND SKIAGRAPHS.

Photographs are generally admissible in evidence when they are shown to have been accurately taken, and to be correct representations of the subject in controversy, and are of such a nature as to throw light upon it.3

* 9 Ency. of Evidence, 771.

4

They are admissible to prove identity of persons; identity and comparison of handwriting; resemblance of animals; scenery and all natural objects; buildings; the condition of a street or sidewalk at the time of an accident; the character of an injury to a person; the situation of land with reference to the grade of a street; as accurate copies of public records which could not be withdrawn from the files; to represent the scene of a crime at the time of its commission, and the locality and conditions at a railroad crossing where a collision had occurred.

Skiagraphs, or X-Ray photographs, taken by the X-ray process by an expert, where proved to have been correctly taken and accurately developed, are admissible in evidence when the expert testifies that they are true representations of that portion of the person to which they relate at the time taken, etc. The expert here testified that he was an X-ray expert and was regularly engaged in taking such photographs for physicians; that he took the negative from which the photograph was developed and that he developed the photograph, and that it was an accurate and correct representation of that portion of plaintiff's chest and body, etc. It was intended to show by the skiagraph that plaintiff's heart was displaced; that the walls of that organ had become thick and that an abnormally heavy tissue had formed on the walls of the heart. The testimony of the X-ray expert who had taken the skiagraph tended to show that the picture correctly represented the condition of the heart of plaintiff. Photographs taken by the X-ray process are admissible

• Udderzook vs. Commonwealth,

76 Pa. St., 340.

C. & J. Elec. Ry. Co. vs. Spence, Vol. XI.-12.

213 Ill., 224, citing 22 Am. & Eng. Ency. of Law, 2nd Ed., 755.

in evidence after proper preliminary proof of their correctness and accuracy has been produced.

SECTION 51. MAPS, CHARTS, DIAGRAMS, SURVEYS.

Maps made by authority of law and filed in the proper office are public documents, and when coming from their legal custodian, and duly certified by him as required by law, are receivable in evidence."

Unofficial maps, showing the place and scene of a crime, when proved to be accurate representations thereof, may be used in connection with the testimony of witnesses in a criminal case. This is for the purpose of better enabling the court and jury to understand the case, by having thus pictorially explained and presented to them the streets, houses, and other surroundings and circumstances connected with the crime, and so that the testimony as introduced may be more easily understood.

It is common practice in the courts to receive in evidence private or unofficial maps, diagrams, models, or sketches, made by the parties themselves for their own private use and convenience, which are shown to be correct representations of places and objects and things which cannot otherwise be as conveniently shown or described by witnesses, as legitimate aids to courts and juries. The correctness or accuracy of such maps or charts need not be shown by the person making them, but any person having knowledge of their accuracy may certify as to their correctness as representations of the locality or objects sought to be shown thereby.

In Lake Street Elevated Railroad Co. vs. Burgess, 200 Ill., 631, plaintiff offered in evidence a pencil diagram or sketch purporting to show the rear end of the front or motor car, the front end of the adPolhill vs. Brown, 84 Ga., 338. 17 Cyc., 412-413. 'People vs. Phelan, 123 Cal., 551.