This is the second appearance of this cause in this court, a new trial having been had since the January *287term. The only ground on which the former judgment was reversed, was that the opinions of unlearned persons, not physicians, as to the influence the mill-dam in question had in producing the disease complained of, were allowed to go to the jury.
Of the various questions now raised, it is not necessary, nor is it proper, to consider but one — all the others having been distinctly passed upon in the previous decision- — for we wish it to be understood that where a question, properly before this court, has, after argument, been solemnly decided here, it is not open for discussion. The legislature, and not the court, must correct the error, if there be any.
The court below refused to allow the following question to be put to the medical witness, Whitney: “Is it not a well-ascertained tact in medical science, that the malaria spoken of will not cross a stream ? ” to be followed up with the proof of the fact, from the scientific knowledge of the witness, that ditches have been made for the express purpose of shutting out a malarious region of country from a salubrious one, and with proof, from the same Imoioleclge, that such ditches have prevented the crossing of malaria into salubrious regions, where it had previously crossed from malarious ones. This question-was objected to by the counsel for the State, on the ground that the witness could not testify to anything but facts within his own knowledge. For a proper understanding of the question and proposition, it is necessary to examine the previous testimony of the witness.
The question itself, stripped of the accompanying proposition, is a very proper one, and probably would not have been objected to. Similar scientific principles were given in evidence by the witness, and well-settled results were allowed to be shown by medical boobs. For instance: Whitney says, “ if a malarious region was covered with water, so long as it was kept submerged it would prevent the extrication of malaria.” “ Stagnant water in a malarious reeion will not tend *288to create disease.” “If water becomes stagnant in a district not malarious, there would be no danger from tbe water.” “ The scum spoken of absorbs the very poison that the water might otherwise evolve.” “ It is generally conceded by the medical faculty, that still water will retain malaria.” Now, these are all scientific principles, or ascertained results, and do not vary in character from the question proper, proposed to be put. How far, then, does the accompanying propro-sition modify it ? Was it intended that the witness should testify from his “ scientific knowledge,” derived from medical and philosophical works, as to facts, or rather examples and particular experiments therein related? or was he to speak from his “scientific knowledge,” derived from his personal examination of certain ditches ? If from the latter, the question was in no wise different from many others which were permitted to be answered. If from the former, the testimony would have been mere hearsay. It would have been receiving as evidence of facts, mere recitals from books, not only unaccompanied with the sanction of an oath, but at second hand. The witness appears, by the bill of exceptions, to have been allowed repeatedly to testify to scientific facts, derived from Iris personal experience and observation; as, “from my own observation, I know that the west and northwest are malarious countries.” “ Water, in passing over a dam, or water-wheel, will evolve any volatile particles it contains.” “ During the latter part of the summer, for the past two years, nearly every family at the commencement of the rapids, four miles above Milwaukee, have had fever and ague and remittents.” From this examination alone, aside from the objetion of the district-attorney, “that the witness could not testify to facts not within his own knowledge,” it is manifest that the purpose of the question and proposition was to extract from the witness evidence of fads derived from his “ scientific,” not his personal knowledge; or, in other words, that ho was to swear to facts, the existence of which he only *289knew from his reading ; and this, upon no principle of evidence, could be admitted. Aside from this, taking this witness Whitney’s testimony as a guide, it is apparent that the question was no way material, as he had already testified that the decomposition, of neither vegetable, aqueous, or animal matter, nor all or either combined, would produce malaria ; thus showing, as far as his testimony was to be relied on, that the disease did not proceed from the mill-pond. The testimony was, therefore, immaterial, and properly rejected. This is the only ground of error that can properly be considered. But as we permitted an argument in regard to the use of what are called scientific books, on a trial, we repeat what we before said on this subject: it is a matter wholly within the discretion of the judge, and is not the subject of a writ of error. An extreme case may be supposed, in which the discretion of the judge, both in the admission and exclusion of bools might be so abused as to require correcting; but this is very far from such a case. A liberal use of medical books seems to have been allowed.
Judgment of the circuil court affirmed.