But he was allowed without exception to show that he had made experiments, and it was only when he undertook to define the nature of the experiment in some detail that he was stopped. We understand the ruling of the court to be in substance that he could not show the nature of the experiment, not that he could not show that he had experi mented. Whether the details of an experiment not otherwise material may be shown as having some bearing as substantive evidence upon a question on trial depends upon the na ture of the question and that of the experi ment. If, for instance, the question be, with reference to the operation, chemical or otherwise, of some natural force which acts uniformly under any given conditions, and the conditions under which the experiment is made are shown to be so similar to those which existed in the case on trial that the court can see that the experiment may be really of assistance to the jury, the details of the experiment may be put in as independ⚫ ent evidence. The true ground of admitting the details and result of such an experiment is that it may be of assistance, but the question whether it may be or whether it may or may not lead to too many collateral questions is largely within the discretion of the court. It is manifest that in view of the nature of the question in dispute, namely, whether the azygous vein was cut by the stab in the back, taken in connection with the difference necessarily existing between the conditions in the case on trial and those under which the experiment was performed and the obvious difficulty, if not impossibility, of ascertaining whether such difference had any material effect upon the result, the court was fully justified in excluding the experiment or any inquiry into its nature.

It is argued however that inasmuch as an expert has the right to explain the reasons for his opinion, it was competent for the witness to state this experiment in detail, to fortify his opinion. But it is settled in this commonwealth that the rule allowing an expert to give the reasons for his opinion has its limitations, and one of them is thus stated by W. Allen, J., in Hunt v. Boston, 152 Mass. 168, 25 N. E. 82: "A party cannot put in evidence incompetent facts under the guise of fortifying the opinion of his witness even if the evidence might have been properly admitted on the cross-examination of the expert." Accordingly it was held in that case that an expert witness on the value of land could not include in the statement of his reasons his knowledge of certain sales in the neighborhood, the sales not being such as were competent evidence of the value of the petitioner's land. The experiment being incompetent as substantive evidence, the court properly excluded all evidence as to its na. ture, even whether made upon a dead or a living body, although offered under the guise of a reason for the opinion of the witness.

13. One Doyle, called by the defendant,

testified that he saw the defendant pass his (the witness') house between 12:15 p. m. and 12:30 p. m. on the day of the murder. On cross-examination he was questioned at considerable length as to whether he had not made previous statements inconsistent with this statement. The defendant then offered to show by a re-examination of this witness, and afterwards by one Hammond, called by the defendant, that the witness, about 10 days after the murder, told Hammond that he saw "the defendant * * * passing by his [the witness'] house, on March 31, 1904, between 12:15 and 12:30, and that he [Doyle] said that he was sure it was" the defendant. This evidence was offered to show that the testimony of the witness Doyle as to this occurrence was "not a matter of recent contrivance." The evidence was excluded, and it is strongly argued by the defendant that the credibility of the witness having been attacked upon the cross-examination the evidence should have been admitted for the purpose for which it was offered. In the books there always has been a difference of opinion as to the admissibility of prior statements to corroborate a witness. In Craig v. Craig, 5 Rawle, 97, there is an instructive | opinion by Gibson, C. J., on this subject, in which some of the leading authorities are mentioned, and the question is briefly but forcibly discussed. In our own state the leading case on this subject is Commonwealth v. Jenkins, 10 Gray, 485. In that case, Graham, a witness called by the commonwealth, had previously testified in the same case in the police court. The defendant attempted to show by cross-examination of this and other witnesses that Graham in testifying in the police court gave a different account of the transaction from that given by him at this trial. The attorney of the commonwealth then, for the purpose of confirming and corroborating the testimony of Graham at this trial, was allowed to introduce evidence that Graham on another occasion, when not under oath and when the defendant was not present, before the examination in the police court, gave substantially the same account of the transaction as that given by him at this trial. It was held that this was error, and that the testimony should have been excluded. In the opinion it was said by Bigelow, J.: "The purpose of the government in offering these statements was to corroborate the testimony of the accomplice, which the defendant had sought to invalidate and discredit by proof that on the preliminary examination before the police court the witness had given a different account of his interviews and dealings with the defendant from that to which he had testified before the jury. Although there is some contrariety of opinion in the books on the question of the competency of such evidence, it seems to us that on principle it ought to be excluded. It has no legitimate or logical tendency to establish the corroboration for which it is offered. How

did the case stand on the evidence of the accomplice, when the government offered the statements objected to? He had testified in behalf of the government to an account of his dealings with the defendant concerning the stolen property. The counsel for the defendant then called witnesses to show that at a previous time he had given under oath a different account of this same transaction. This evidence was offered, not for the purpose of proving the truth of such previous statements, but to show that he was unworthy of belief, inasmuch as he had given two inconsistent accounts of the same transaction, one of which was necessarily untrue.

*

It did not relieve the difficulty, or in any way corroborate the last story told by the witness, to show that he previously had made similar statements of the transaction. The discredit arising from the fact that he had made contradictory statements remained untouched. The contradiction was not disproved by such evidence, and this was all that the prior statements were offered to establish.

*

* Such a corroboration is altogether too slight and remote." After proceeding further to show why the general rule should be adopted, the opinion goes on to say that the decision in the case "is not to be understood as conflicting with a class of cases, in which a witness is sought to be impeached, by cross-examination or by independent evidence, tending to show that at the time of giving his evidence he is under a strong bias or in such a situation as to put him under a moral duress to testify in a particular way. In such case, it is competent to rebut this ground of impeachment and to support the credit of a witness by showing that when he was under no such bias, or when he was free from any influence or pressure, he made statements similar to those which he has given at the trial. Another similar class of decisions

is also to be distinguished from the case at bar, namely, when an attempt is made to impeach the credit of a witness by showing that he formerly withheld or concealed the facts to which he has now testified. In such cases, it is competent to show that the witness, at an early day, did declare

the facts to which he has testified." It was held that the case was not within either of these exceptions, and accordingly that the evidence was improperly admitted.

At the time the evidence in the case at bar was excluded, there had been no attempt to impeach the credit of Doyle except by his cross-examination, and it therefore becomes necessary to examine that to see if there was any other impeachment of his credit than that which necessarily and ordinarily would arise from the fact that he had made contradictory statements. In his cross-examination, he stated that at the office of the Attorney General, in the presence of a stenographer and several other persons whose faces he could not recall, he had made a statement of the case; that he had testified before the

grand jury; that he could not tell how many times since then he had talked over the fact of the defendant's passing his house; that he had talked the matter over with one Ducey, an officer who was assisting in the preparation of the defense; that ever since he had talked with the state officers about the case, he had expected to testify; that he intended to tell the truth before the grand jury, and also at the office of the Attorney General in Boston, and, that so far as he remembered, his present testimony was in accordance with that given by him before the grand jury; that he remembered that, before the grand jury, he was asked whether he saw the defendant on the day of the murder; that he replied in the affirmative, and said that he saw him two different times, "once between 1:30 and 1:45," at the Metropolitan boathouse, in company with one Bourne, and next at 3 o'clock; that he did not remember that he was asked whether he had seen the defendant at any time "except that once, and with Bourne," but he would not say he was not asked that question; that he did not know whether he then said that he "couldn't say for sure" whether he saw him go down past his (the witness') house; that he would not say he did not say that; and that he would not say whether he did not say that he could not tell whether the defendant went by the house or not. And, finally, this question was put to him: "Now didn't you say in my office and to other people that you couldn't tell who the man was that passed your house, that you couldn't describe his dress, that you couldn't tell whether he had a beard or not, and you couldn't tell which way he was going? Haven't you said all those things before you came on to the stand here today?" To this question, he said in substance that he did not know, would not say whether he had or had not.

The first question is whether in this examination it appeared that the witness ever had made any statements inconsistent with his then present testimony about seeing the defendant going by the witness' house. As to his testimony before the grand jury he said that while testifying there he intended to tell the truth and that so far as he could recall his testimony there it was the same as here. So far there is no evidence of contradiction. Upon being further pressed he finally said that he did not know whether he there said "I can't say for sure whether I saw him [the defendant] go down past our house," although he would not say that he did not then say so; that he did not remember that he said it. Here, too, there is no direct contradiction of his present testimony. If, however, it be assumed that, when a witness upon being asked whether he formerly made a certain statement, replies that he does not know whether he did or not, but that he will not say he did not, this may be an admission by implication that he did say it, or that upon such evidence it may be le

gitimately inferred that he did say it, still we have at the utmost here evidence that before the grand jury the witness said that he could not say for sure whether he saw the defendant go past his house on the day of the murder. This was a simple contradictory statement at the most. The same remarks may be made about the effect of the answer of the witness to the general question above quoted in full, with reference to whether the witness had not said in the Attorney General's office, and to other people, that he could not tell who the man was who passed his house, nor which way he was going, nor how he was dressed. If the answers of the witness that he did not know, but would not swear whether he had or not are to be regarded as sufficient to warrant the inference that he had made such statements, still here, as in the matter of his testimony before the grand jury, the statements are simply contradictory of his testimony at the trial; and within the doctrine laid down in Commonwealth v. Jenkins, 10 Gray, 485, they do not justify the admission of the evidence offered by the defendant. It is argued, however, that the situation was such as to bring the offer within the exception to this general rule, namely, when an attempt is made to impeach the credit of a witness by showing that he formerly withheld or concealed facts to which he has now testified, or in other words where it may be contended that the testimony of the witness is a matter of recent contrivance. In a certain sense it is always true that every prior statement of a witness inconsistent with the one made by him at a trial has or may have a tendency to show that the latter is a matter of recent contrivance. It is certainly a recent statement and may be recently contrived. If the exception to the rule is to be so broad as to permit in every such case the introduction of prior consistent statements to prop up the credibility of the witness, the exception would very soon abolish the general rule. The general rule is founded upon sound policy. The corroborative evidence, even when admitted, can have, at most only a very indirect bearing upon the credibility of the witness, while from its very nature it may be likely to influence the jury as substantive evidence of its own truthfulness. And since the danger that the evidence will have such an illegitimate influence is so great, it is important that the general rule should be adhered to unless the case appears clearly within the exception.

It is to be noted that this is not a case in which the commonwealth attempted to impeach the credit of the witness, by showing that he formerly withheld or concealed the fact that he had seen the defendant pass his house. The position of the commonwealth was that he had made contradictory statements about that, and the admissions of the witness (if admissions they may be called), wer simply to that effect. It was not a where he had failed in former state

case

ments to speak on the subject, but where in speaking on the subject he had made prior statements inconsistent with his testimony at the trial. In other words, it was a simple case of contradictory statements, and so far was within the general rule. Nor do we think that the admission of the witness that he had talked with the officer who assisted in the preparation of the case is sufficient to bring the case within the other exception arising out of a claim of strong bias or sort of moral duress stated in Commonwealth v. Jenkins, ubi supra. We think that these two exceptions, which were recently considered in Griffin v. Boston, 188 Mass. 475, 74 N. E. 687, should be construed with some strictness, so as not to nullify the general rule. Sometimes it will appear, from the nature of the evidence and the course of the cross-examinations, that the cross-examining counsel intends to argue against the truth of the testimony, because the witness is not shown to have spoken previously of the matter when, if it were true, he would have been likely to speak of it. To meet such a contemplated argument, it may well be proved that he did speak of it. Or something of recent occurrence may appear, which would be likely to create a strong bias in the mind of the witness, and to put him under a kind of moral duress to testify as he does. To answer the argument from such a fact, it may be shown that he said the same thing before the occurrence. The admissibility of the testimony depends upon the previous introduction of such facts and the existence of such conditions. Whether the course of the trial has been such as to require a statement of what the witness had previously said, to meet an attack upon his testimony, founded on either of these peculiar conditions, is primarily a question of fact, to be decided by the presiding judge. His decision upon such a question ought not to be set aside by an appellate court unless it is plainly wrong. To use a common expression, the reason for which has just been stated, the admission or exclusion of such testimony rests largely in the discretion of the trial court.

The court had the right to infer from the cross-examination that this was the ordinary case of an attempt to impeach the credibility of a witness by showing that he had made prior statements inconsistent with his then present testimony, and that the general rule existing in this commonwealth should be applied. In applying the rule under this interpretation of the cross-examination, the court committed no error. It is contended by the defendant that the Attorney General in his closing argument went further, and made remarks inconsistent with this view of the cross-examination, but it does not appear that he pressed the argument against the witness to any greater extent than is allowable in the ordinary case of inconsistent statements of a witness. And in any event this could not affect the view which at the

time of the offer of the evidence the court might rightfully take of the cross-examination.

14. The question to Thode, the photographer who had made the enlarged photograph, was rightfully excluded. The witness had already testified that he could not say whether the pin shown to him was or was not that which appeared in the photograph. It is sufficient to say that, both pins and the enlarged photograph being all before the jury, it does not appear that the witness could see any better than the jury which pin was shown in the photograph. It was not a matter for expert testimony.

15. So far as respects the refusal of the court to give the fourth, fifteenth, sixteenth and seventeenth instructions requested, we have examined the charge with special reference to the subject-matter of these requests, and are of opinion that while the court did not give the rulings in the language requested, still it gave them in substance, and with great clearness and accuracy stated the principles of law applicable thereto. The court committed no error in the manner in which it dealt with these requests.

16. Upon the subject of deliberately premeditated malice aforethought, much was said in the charge. Very clearly and very emphatically the jury were told that in order to convict the defendant of murder in the first degree they must find beyond a reasonable doubt not only that he committed the homicide, but that he did it with deliberately premeditated malice aforethought. The court then proceeds as follows: "The words 'deliberately premeditated malice aforethought' mean simply thought upon, resolved upon beforehand, not a thing done suddenly, not a thing that comes into the mind of a sudden, and is done before there is time to think about it, but a thing thought of, or planned some time before, or if not planned some time before, yet thought upon long enough before the act is done so that it can reasonably be said to have become a purpose of the mind. No particular length of time is necessary. If it is thought upon reasonably beforehand, that is enough to warrant you in finding the crime to be murder in the first degree. Accordingly the chief justice of the highest court in our state said in one case, in language which I adopt and give to you, "To premeditate is simply to meditate beforehand. It need not be for a long time. It merely requires time to form a clear intent. For example, a robber with a dirk or pistol turns a corner and meets a bank messenger with a roll of bills. In a moment he determines to get it. The next moment he shoots or stabs the messenger dead, takes the package and flees. His malice was deliberately premeditated, though it occupied only a few seconds; for it was a cool act of the will, and is unlike the intent stimulated by a sudden act of quarrel, where one kills another suddenly, not having intended

violence beforehand.' And to apply that principle, gentlemen, to this case, if you should find it shown with the requisite degree of certainty that this prisoner went to the Page house for the purpose of stealing something, or with any other unlawful purpose, but carried with him a deadly weapon for the purpose of taking human life, if that should be necessary to make his escape or to remove a witness to his guilt, or to carry out his unlawful purpose, and if you should find that he did take the life of Mabel Page in pursuance of that purpose thus existing in his mind when he started upon the execution of his first or principal purpose, then, gentlemen, you would be warranted in saying that he committed the crime with deliberately premeditated malice aforethought, and that it was shown that he had been guilty of murder in the first degree. To constitute deliberate premeditation, you see, there must be a design, or plan, actually formed and resolved upon before the act, and the murder must be committed pursuant to the design or plan which had been thus formed. And it must be shown that the murder was the result of a design or plan formed after the prisoner had thus made it the subject of deliberation or reflection, although in view of the quickness with which the mind may act, this deliberation, or reflection, may have been measured by seconds, only by an appreciable interval. The act must have been deliberately thought upon, resolved upon, beforehand, long enough before the act was done to warrant the inference that it was so thought upon and resolved. If accordingly, having first found that the prisoner is guilty of the crime of murder, you shall further find that he committed the murder with deliberately premeditated malice aforethought, then he is guilty of the crime of murder in the first degree, and you will say so by your verdict; if you do not find this further fact to be proved beyond a reasonable doubt, then your verdict will be only guilty of murder in the second degree."

After the case had been submitted to the jury, the court, in reply to requests from them for more light, further instructed them as follows: "Answering your question, gentlemen, exactly as you put it, deliberately premeditated malice aforethought cannot take place instantly with the act, if by that is meant that the two come exactly together. To constitute deliberately premeditated malice aforethought the purpose must have been formed so that you can say that it did distinctly precede the act. It makes no difference whether the interval between them was long or short, if it can be said that the purpose did distinctly precede the act, so that it became a fixed purpose of the mind, and was then executed by the act in pursuance of that purpose. As in the illustration which you will remember that I gave to you-a robber with a dirk or a pistol turns a corner. He has no intention of committing

crime when he turns the corner, but, as he turns the corner, he meets a bank messenger with a bundle of bills; a few seconds would suffice, perhaps one second would suffice, for the messenger to pass him in safety; but the minute that his eye lights upon that messenger with the roll of bills which the messenger is carrying, he conceives the purpose of robbery, and of taking the life of the messenger to obtain that money. He shoots or stabs the messenger to the heart, seizes the money and flees. That was deliberately premeditated malice aforethought, although scarcely an appreciable interval of time separated the formation of the purpose from its execution. But it was deliberately premeditated malice, although the time was so brief because of the quickness with which the mind can work, and because the purpose was formed, was resolved upon, became a fixed purpose, before it was executed. It was the subject of resolution, of deliberation, although the resolution, the deliberation, were instantaneous-almost at any rate instantaneous-yet there was a real interval between them, because the act done in pursuance of the purpose could not have been carried into execution, could not have become an act, had it not been that the purpose was first formed; for that is the way in which I have stated the supposition. And so in this case if this prisoner did unlawfully take the life of this woman with malice aforethought, and if he did so in pursuance of a plan, a purpose, a resolution which he formed to do so, if, for example, to make a supposition, he saw or thought he saw that to make his escape to avoid the danger of an accusation of crime against him he must put her out of the way, and if he made up his mind, if he formed the purpose, the resolution, to put her out of the way for his protection, and in pursuance of that resolution, of that deliberate purpose, formed with a resolution and with deliberation although quickly formed, he executed that purpose and wrongfully took her life, you would be warranted in saying that it was done with deliberately premeditated malice aforethought, even though the fatal blows followed at once after the determination to inflict them, immediately after the formation of the purpose, provided, gentlemen (and I pray you to follow every word that I say). provided the purpose was distinctly formed and concluded upon, provided the plan was formed before it was acted upon, so that you could fairly say that it became a distinct resolution of the mind, a distinct purpose formed upon reflection, though upon the speediest reflection, formed upon deliberation, though upon the speediest deliberation. If those things, gentlemen, are found, deliberately premeditated malice aforethought is properly to be inferred. If those things are not found, although you shall have found that malice aforethought existed, you would not say that deliberately premeditated malice aforethought was to be properly found."

MASS.DEC.73-77 N.E.-35

The defendant excepted "to that portion of the definition of murder in the first degree above recited;" also to the definition of the phrase "deliberately premeditated malice aforethought;" and especially to that part of the charge in which the illustration as to the bank messenger is given. The phrase first appears in St. 1858, p. 126, c. 154. Prior to the passage of that statute the commonlaw definition of murder was the one in force in this commonwealth. Murder at common law was murder here. In the charge of Shaw, C. J., in Commonwealth v. Webster, 5 Cush. 295, 52 Am. Dec. 711, the trial of which took place in 1850, will be found a very clear exposition of this crime. There was only one degree, and it was punishable with death. Rev. St. 1836, c. 125, § 1. By St. 1858, p. 126, c. 154, now Rev. Laws, c. 207, § 1, murder committed with deliberately premeditated malice aforethought, or in the commission of an attempt to commit any crime punishable with imprisonment for life, or committed with extreme atrocity or cruelty," was declared to be murder in the first degree and punishable with death. Murder not appearing to be in the first degree was declared to be murder in the second degree, and punishable with imprisonment for life. Shortly after the passage of the statute, it was held that it did not change the commonlaw definition of murder as recognized by our courts, but simply manifested the intention of the Legislature to consider murder as a crime "the punishment of which may be more or less severe according to certain aggravating circumstances which may appear at the trial." Commonwealth v. Gardner, 11 Gray, 438, 444; Commonwealth v. Desmarteau, 16 Gray, 1. In the case at bar the only ground upon which it was contended by the commonwealth that this was murder in the first degree was that it was committed with deliberately premeditated malice aforethought. We are of opinion that in defining that phrase, the court laid down the law as it has been held ever since the passage of the statute of 1858, and that both by reason and by authority it is sound. The reasons for such an interpretation of the phrase are so clearly stated in the language of the various judges who have had occasion to expound to jurors the law on this subject that it seems necessary to do little more than quote their language.

One of the earliest cases after the statute of which we have any accessible report is Commonwealth v. Andrews. That case was tried in October, 1868, in this court, before Chapman, C. J., and Foster, Wells, and Colt, JJ., being four of the six justices of which this court was then composed, and sitting as a full court. In charging the jury, Chapman, C. J., speaking for all the judges present, after defining malice, proceeds to speak of the word aforethought as used in connection with malice, in the common-law definition of murder, and uses the following lan