Fowler, J.
A variety of questions are raised by the ease, and have been discussed by counsel, to only a portion of which have we found it necessary to direct our attention in arriving at a conclusion.
I. As a general rule, the opinion of witnesses is not admissible in evidence. They must speak to facts within their knowledge. But, upon questions of skill or science, with which a jury may not be supposed to be familiar, men who have made the subject matter of inquiry the object of their particular attention or study, are competent to give their opinion. It must, however, be first shown that they are skilful or scientific men, or at least that they have superior actual skill or scientific knowledge in relation to the question, before their opinions can be competent. Mere opportunity for observation is not sufficient. 1 Phill. Ev. (Edwards’ Ed.) 778, ch. 10, sec. 4, and notes; Rochester v. Chester, 3 N. H. 349; Robertson v. Stark, 15 N. H. 109; Beard v. Kirk, 11 N. H. 397; Concord Railroad v. Greely, 23 N. H. 237 ; Pickard v. Bailey, 26 N. H. 152; Marshall v. Columbian Ins. Co., 27 N. H. 157; Lincoln v. Barre, 5 Cush. 590; Lusk v. McDaniel, 13 Ire. 485; McLean v. State, 16 Ala. 672; Luning v. State, 1 Chandler (Wis.) 178.
In the present case, Stephen Walker was permitted to give his opinion as to the quality of the soap-stone in the quarry in controversy. This was peculiarly a question of scientific skill and knowledge, which the witness was not shown to possess. It only appeared that he had been more or less engaged for forty years in quarrying soapstone, principally from two localities in Yermont; that he had manufactured soap-stone into pipe for aqueducts, more or less for about twenty years ; that he had worked a year and a half in manufacturing articles from soapstone for the New-York mai’ket, and that he had visited two soap-stone quarries in New-Hampshire, one in Massachusetts, and another in Yermont, besides that concern[60] ing the quality of whose product he testified. But it did not appear that he had ever devoted any time or study to an investigation of the composition and characteristics of soap-stone, or made any particular observations on that subject, so as to be better qualified to give an opinion on the scientific question propounded to him, than any member of the jury. For aught that is shown in the case, he • might have been a mere day laborer, mechanically performing the task assigned him; scarcely more intelligent than the material on which he wrought, and hardly better qualified to give an opinion of the qualities of that material than the tools he employed in working it. He was not, therefore, shown to possess that scientific or actual knowledge of the subject in relation to which he was inquired of, which made his opinions competent evidence; and they were improperly admitted. He was certainly not shown to possess so many qualifications as an expert, as Arioch Wentworth, whose opinions, when offered by the defendants, were, as we think, under the circumstances, properly rejected.
II. The statement in the deposition of Orin Bronson of what Taylor said in relation to the stone Bronson carried away from the quarry, was mere hearsay, and inadmissible against the defendants’ objection on trial — this portion of the deponent’s answer not having been responsive to the interrogatory proposed to him.
If a deposition contain mere hearsay of a fact upon which hearsay is not evidence, it cannot be received as proof of that fact; and hearsay is uniformly holden incompetent to establish any specific fact which is in its nature susceptible of being proved by witnesses who can speak from their own knowledge. 2 Phill. Ev. (Edwards’ Ed.) 251, ch. 1, sec. 7; Pellatt v. Ferrars, 2 B. & P. 548; 1 Gr. Ev., sec. 99.
It is contended that the declarations of Taylor were competent as admissions of the defendants, or some of [61] them, whose agent he was in the matter as to which they were made. But the case does not find Taylor to have been the defendants’ agent in relation to the stone which the witness carried away. He was the foreman of the hands employed by the defendants -in quarrying stone, and had charge of that department; but it does not appear that he had any authority or agency whatever connected with the sale or delivery of stone from the quarry, or that he was ever employed or authorized to make any representations of the character or value of the stone quarried. His declarations on that subject, therefore, were mere hearsay ; he was a competent witness, and might have been called by either party; and the witness having introduced this clearly incompetent matter into his answer when the same was not called for by the interrogatory, the defendants had a right to take and insist upon the substantial objection to its being read in evidence on trial, although they had omitted to make any objection to it at the caption.
ni. The statement of David M. Parker, made a year or two before the alleged conspiracy to defraud the plaintiff was charged to have been entered into, to the effect that the Franeestown quarry would not come into competition with the one as to the sale of which the conspiracy was alleged to have been afterward formed, was clearly inadmissible. The case finds there was no evidence whatever that went to connect David M. Parker in any way with the alleged fraudulent representations set forth in the declaration, and relied upon to support the action, except that, being a brother of one of the other defendants, and owning the quarry, he authorized that brother to negotiate a sale of it to any person, upon such terms as might be satisfactory to him ; while the evidence tended to show that the brother made the alleged fraudulent representations, during the negotiation carried on by himself and the third defendant, whom he employed to assist him in [62] effecting the trade which resulted in a sale of the property to the plaintiff.
Now, it is a well established rule, that where several persons are proved to have combined together for the same illegal and fraudulent purpose, any act done by one of the party, in pursuance of the original concerted plan, and with reference to the common object, is, in contemplation of law, the act of the wdiole party, and it follows, as a corollary from this rule, that any writings or verbal expressions, being acts in themselves, or accompanying and explaining other acts, in furtherance of the common design, and so part of the res gestee, which are brought home to one conspirator, are evidence against the other conspirators, provided it sufficiently appear that they were made and used in furtherance of the common purposes of the conspiracy. But the conspiracy and common design must be shown, else the statements or declarations made by one of them in the absence of the others, but for the furtherance of that common design, cannot be given in evidence against the others. Proof of the plot or combination must precede, accompany or follow proof of declarations made by either of the alleged conspirators, to render them competent against the others; it must be shown that the conspiracy or combination was entered into before the declarations were made, though the conduct, acts and declarations of the separate individuals in the planning or execution of the joint scheme may be shown as evidence of the common design. To be admissible, the acts and declarations must be those only which were done and made during the pendency of the wrongful enterprise, shown to have been undertaken jointly, and in furtherance of its objects. 1 Gr. Ev. 80, sec. 111, and notes; 1 Phillipps’ Ev. (Edwards’ Ed.), ch. 8, see. 1, and notes; The People v. Parish, 4 Den. 153; Williamson v. Com., 4 Gratt. 547; State v. Simons, 4 Strobh. 266; Regina v. Mears, 1 E. L. & E. 581; State v. Ripley, 31 Me. 386; Glory v. State, [63]*638 Eng. (Ark.) 236; Apthorpe v. Comstock, 2 Paige 482, 488; Craige v. Sprague, 12 Wend. 41; Babb v. Cleason, and Willes v. Farley, 3 C. & P. 395; Patten v. Gurney, 17 Mass. 182; Lovell v. Briggs, 2 N. H. 218; Sheple v. Page, 12 Vt. 519; Talbot v. Caines, 5 Met. 520; Brannock v. Bouldin, 4 Ire. 61.
In the present case, the statement of David M. Parker was made at the time he purchased the quarry, a year or two before the sale to the plaintiff, and accompanied his act of purchase. There could, therefore, as we conceive, be no pretence that this declaration was made during the pendency of the combination or conspiracy to defraud the plaintiff in the sale of that quarry, i f any existed, or that it accompanied and explained any act done in furtherance of the common design of such conspiracy, if one afterward existed, and quite as little that it was a declaration accompanying and explaining any act done by David M. Parker himself, in plotting or arranging such contemplated conspiracy or combination. It was, therefore, clearly incompetent and inadmissible.
IV. The question proposed by the plaintiff to Arioch Wentworth in his deposition was manifestly leading. It suggested a material fact in such a way as to indicate very decisively to the witness that he was expected to verify its truth by his answer, and might have been answered by a simple affirmative or negative. It was an argumentative or pregnant interrogatory, assuming the existence of a particular condition of the soap-stone, which had not been proved, but which the witness was evidently expected to establish. 1 Gr. Ev., sec. 434; Bartlett v. Hoyt, 33 N. H. 165; Dudley v. Elkins, 39 N. H. 78; Spear v. Richardson, 37 N. H. 23.
A question is leading which instructs the witness how to answer on material points, or puts into his mouth words to be echoed back, as was here done, or plainly suggests the answer which the party wishes to get from him, whether [64] it be put in the alternative form or not. 2 Phill. Ev. (Edwards’ Ed.), ch. 10, sec. 1, and notes; People v. Mather, 4 Wend. 229; 1 Stark. Ev., 123; Courteen v. Touse, 1 Camp. 43 ; Snyder v. Snyder, 6 Binn. 483.
Y. It was wholly immaterial to the issue between the parties, whether or not the letter of Wentworth & Chandler to the plaintiff, declining to take of him more stone because he had none which would answer their purpose, was written in reply to one from him couched in civil or uncivil terms, and therefore it would not have been competent for the plaintiff to have contradicted even the defendants’ witness upon that point by introducing the letter or otherwise. The only fact that could have been important or material was, that they declined to purchase more stone, because they were of opinion that he had none of sufficiently good quality to answer the purpose for which they wished to employ them. Whether or not the letter announcing this conclusion was in reply to one from the plaintiff, which they justly or unjustly regarded as uncivil, and for that reason was designed to discontinue further business intercourse on their part with him, was of no consequence to the issue between the parties to this suit. The letter was then offered and received to contradict the cross-examination of the plaintiff’s own witness in regard to an immaterial matter, and was itself wholly immaterial, so far as any thing appears from the case. It was, therefore, improperly admitted; but as it seems to have been entirely immaterial, and we are unable to perceive how the defendants could have been prejudiced by its introduction, its improper admission furnishes no sufficient ground for setting aside the verdict. Clement v. Brooks, 13 N. H. 92; Winkley v. Foye, 28 N. H. 519; 33 N. H. 171.
YI. The present action' was clearly brought against the defendants for a joint conspiracy or combination by them to cheat and defraud the plaintiff in the sale to him of the soap-stone quarry, and its appurtenances. As we have [65] before seen, if tbe plaintiff proved that the defendants had first entered into a combination for this wrongful and fraudulent purpose, the subsequent acts and representations of each of the conspirators, in furtherance of that purpose, would be the acts and representations of them all, and competent evidence against them all on trial. But proof of the conspiracy, or wrongful combination, having been first entered into, must precede, or certainly accompany or follow that of the acts and representations, otherwise the acts and representations of one could not be competent evidence of the guilt of the others. Only those acts and declarations of one conspirator are admissible to charge another, which form part of the res gestee of the offence; that is, which were made or done during the pendency of the wrongful or criminal enterprise shown to have existed, and in furtherance of its objects. The acts and declarations of a conspirator, accompanied. by sufficient proof of the fact of a conspiracy having been entered into, may be given in evidence to charge his fellow, bul; subject always to this limitation, that the acts and declarations admitted should be those only which were made and done during the pendency of the wrongful or criminal enterprise, and in .furtherance of the common design. They must be concomitant with the principal act, and so connected with it as to form part of the res gestee. Browning v. State, 30 Miss. (1 George) 656; Patton v. Ohio, 6 Ohio N. S. 467.
Now, if we understand the.ground of the motion for a nonsuit as to David M. Parker, it was, substantially, that no evidence had been offered tending to show that he had ever conspired or combined with the other defendants to cheat and defraud the plaintiff; that he made no representations personally, and it only appeared that he was the brother of one of the other defendants, and being the owner of the property, had authorized his brother to dispose of it to such person and on such terms as he pleased. In [66] this state of things the court seems to have ruled that notwithstanding the want of any evidence tending to show that David M. Parker entered into or in any way participated in any combination or conspiracy with the other defendants, for the alleged illegal and fraudulent purpose charged against all of them; and although he never authorized or was guilty of any fraudulent acts or representations, he might be held answerable jointly with them in this action, by reason of the alleged false and fraudulent representations made by his brother and Reding, notwithstanding he had no knowledge of them prior to the delivery of the deed to the plaintiff.
Thus understood, we think the ruling of the court to have been erroneous. If no conspiracy and common design to cheat and defraud the plaintiff were shown to have existed between David M. Parker, his brother, and Reding, but "William M. was merely the agent of David M. to dispose of his property, and employed Reding to assist him in so doing, as the facts stated in the case would seem to indicate to have been the true character of the transaction, David M. could not be holden responsible as á joint conspirator with his brother and Reding, solely by reason of unauthorized, false and fraudulent acts and representations made by them ; — their false and fraudulent representations, if made without his knowledge and authority, or privity, and without a common design and combination between him and them to defraud and cheat, could not be received as evidence of his guilt as a joint conspirator and defrauder with them, however he might be holden separately responsible as principal, for the wilfully false and fraudulent unauthorized acts and representations of his agent.
The gist of an action on the case in the nature of a conspiracy, is not the unlawful or wrongful agreement and combination of the defendants, but their joint fraudulent acts, and the consequent damage resulting from the execu[67] tion of this agreement. Both the joint fraudulent acts and the consequent damage must be proved, to entitle the plaintiff to recover. The conspiracy charged is important only as giving character to the individual acts of the parties to it. It must be shown that all combined or conspired, before the acts or declarations of one can be competent evidence against all. It is not necessary to prove that all came together, and actually agreed in terms to have a common design, and pursue it by common means. If it be proved that the defendants pursued by their acts the same common object, often by the same means, one performing one part and another another part of the same plan, so as to complete it with a view to the attainment of the same common result, the juiy will be justified in the conclusion that they were engaged in a combination or conspiracy to effect that result. But, in the absence of any proof of a conspiracy formed or a combination entered into, and of any acts or declarations of one of the alleged conspirators, made and done while the alleged conspiracy was pending, in fui’tberanee of the alleged common design, it is quite clear that he cannot be found guilty solely upon the acts and declarations of other alleged conspirators. As we have before seen, those acts and declarations are admissible against him solely on the ground that, by combining or conspiring together, the conspirators have jointly assumed to themselves as a body the attribute of individuality, so far as regards the prosecution of the common design; thus rendering what is knowingly and wilfully done and sai^by any one of their number in furtherance of that design a part of the res gestee, and therefore the act and saying of all. 1 Gr. Ev., secs. 92, 93, 94, and notes; Regina v. Murphy, 8 C. & P. 297; Regina v. Shellard, 9 C. & P. 277.
The ruling of the court below having apparently gone upon the assumption that David M. Parker might be holden liable as a joint conspirator with his brother and [68] Reding, solely by reason of tbeir alleged false and fraudulent conduct ánd representations, although he had neither conspired or combined with them to defraud the plaintiff, nor had in any way participated in or had any knowledge of, or given any authority for their alleged"false and fraudulent conduct, representations and purpose, was therefore erroneous. The master and his servant, or the principal and his agent, cannot be holden jointly liable in an action of tort for the unauthorized fraudulent acts or representations of the servant or agent, committed or made without the knowledge and concurrence of the master or principal. Parsons v. Winchell, 5 Cush. 592; Wright v. Wilcox, 19 Wend. 343; 1 Pick. 62.
In an action ex delicto, the act complained of must be the joint act of all the defendants, either in fact, or in legal intendment and effect. But the act of a servant or agent is not the act of the master, or principal, even in legal intendment or effect, unless the master or principal previously directs or subsequently adopts and ratifies it. Parsons v. Winchell, 5 Cush. 593.
There is no contribution among joint wrong doers, and if David M. Parker could be found guilty as a joint conspirator and defrauder with the other defendants, solely upon evidence of the unauthorized fraudulent acts and representations of his agent and the person employed by him to aid in effecting a sale, and he should be compelled to satisfy the judgment recovered against all, he would be entirely without remedy for reimbursement, or even contribution against the other defendants, however utterly unauthorized and disapproved those fraudulent acts and ;representations might have been. Unless, therefore, the plaintiff be able to show the joint participation of David M. Parker in the alleged fraudulent purpose and design of the other defendants, it would be manifestly unjust that he should be holden liable with them in the present action, even though he might be clearly liable, if sued [69] separately, for the damage resulting from the unauthorized fraud of the agent employed by him to sell his property ; since it is well settled that a principal has a remedy over for damages he may be compelled to pay in consequence of the unauthorized misfeasances and malfeasances of his agent. Merryweather v. Nixan, 8 D. & E. 186; Vosc v. Grant, 15 Mass. 505, 521; Campbell v. Phelps, 1 Pick. 62.
VII. An action for deceit and fraud in the sale of property, or an action for conspiracy to defraud in the sale of property, can only be sustained where some affirmation or representation, wilfully false, or some designed and positively fraudulent artifice is directly proved, or is necessarily to be presumed from the circumstances attending the transaction itself, by means whereof a damage resulted to the plaintiff. Com. Dig., Case for.Deceit, A. (8), and authorities; Emerson v. Brigham, 10 Mass. 197; Van Bracklin v. Fonda, 12 Johns. 468; Sheple v. Page, 12 Vt. 519.
Upon the execution and delivery of the deed by David M. Parkervto a third person, for the plaintiff, the payment of §100 and the making of notes by the plaintiff' for the balance of the purchase money, §4000 of which was secured by a mortgage of the premises conveyed, and the deposit of those notes with that third person, under the agreement set forth in the case, the trade between the parties was finished and the sale complete, so far as the plaintiff was concerned; and, in the absence of fraud, there being no pretence of any express warranty, the property purchased was afterward at the risk of the plaintiff. No subsequent occurrence could transform what was then a fair and honest transaction into a false and fraudulent one. The deed of David M. Parker gave to the plaintiff all he had purchased, and if it were afterward discovered by him to be less valuable, by reason of latent defects in the quality of the stone, than he had supposed, or the defendants had honestly represented, in the absence of fraud the plaintiff was obliged to suffer the loss without redress. [70] He could not on that account rescind the contract. He could not resist the payment of the notes, because the soap-stone proved less valuable for certain purposes than had been honestly anticipated by both parties. If the plaintiff had been notified by the defendants of the information they had received in relation to the newly discovered incapability of the stone to endure the action of fire, it would neither have furnished any ground for rescinding the contract, nor any cause of defence to an action upon the notes, since it could at most only have tended to show a partial failure of consideration, contingent and uncertain in its extent. 2 Kent. Com. 478, 479, and authorities ; Co. Litt. 12 (a); 2 Black. Com. 452 ; Bac. Abr., Action on the Case, E.; 2 Com. on Cont. 268.
It could not, therefore, be any evidence of actual fraud in the defendants, resulting in damage to the plaintiff, not to communicate to the plaintiff information which could do him no good, and furnish him no relief in relation to the contract he had made and finished ; much less could their neglect to communicate such information operate back, and not only make the previous representations, made in good faith, and with an honest belief in their truth, wilfully false and fraudulent, but justify the jury in finding an original conspiracy and combination to defraud between all the defendants, of which no evidence had previously been offered, and such a joint participation of all the defendants, in carrying out the common design and purpose of such conspiracy and combination, as to make the acts of one evidence of the guilt of the others. In order to sustain the present action, the plaintiff must prove a positive fraud to have been committed by the defendants jointly, or by such of them as are holden responsible, and a damage resulting to himself therefrom. He must show not only that the representations made to him were false, and known at the time to be so, but that they were intended to deceive him, and that he believed [71] and acted upon them as true. It is not sufficient to prove that they were unwarranted and groundless; it must be shown that those who made them did not believe them to be true. Besides, the representations must have been such as were likely to impose upon a man of ordinary prudence and caution, and to throw him off his guard on a point or points where he might properly and judiciously be expected to rely upon them, and not upon his own sagacity and means of observation or investigation. Ide v. Gray, 11 Vt. 615; Sheple v. Page, 12 Vt. 519; Tryon v. Whitmarsh, 1 Met. 1; Mamo v. Gardner, 3 Brev. 31; Emerson v. Brigham, 10 Mass. 197; Hoitt v. Holcomb, 32 N. H. 185.
YIII. We are not aware of any principle upon which the paper prepared by the plaintiff and exhibited to Reding could properly have been permitted to go to the jury as substantive evidence. It was not made at the time of the representations by one who then knew it to be correct; it was not a part of thé res gestee in any sense of that term; it would seem to have been a document prepared by the plaintiff himself, from his recollection of the conversations with Reding; and there was a conflict of evidence as to whether or not the paper produced on trial was the original, or had been copied or altered from the original draft. At most, it was only a written document, prepared by one party as a witness, offered and permitted to go to the jury with his testimony as substantive evidence for the purpose of confirming it, and impeaching the testimony of an adverse party in conflict with it. It seems to us to have been improperly admitted for this purpose.
IX. The instructions of the court below, as to the rule of damages in case the jury found the sale to have been effected through the alleged conspiracy and combination of the defendants to cheat and defraud the plaintiff, appear to have been substantially correct. Indeed, it may be considered as well settled in this State, that the proper meas-[72] tire of damages, in actions for fraud and deceit in the sale of real as well as personal property, where the purchaser retains the property, under ordinary circumstances, is the difference between the actual value of the property, and its value as represented to be at the time of "the sale, the price paid being very strong, but not absolutely conclusive evidence of the value of the property as it was represented to be. Aggravating circumstances of indignity and insult, of abusive language and conduct attending the transaction, if properly alleged, might undoubtedly be given in evidence, to show the whole extent and degree of the injury, and thereby increase the damages, Fisk v. Hicks, 31 N. H. 535, and authorities; Cary v. Graman, 4 Hill 625, and cases cited.
There are various questions as to the sufficiency of the several counts of the plaintiff’s declaration, raised by the motion in arrest of judgment, which it is unnecessary now to consider, inasmuch as the verdict must be set aside for the improper admission of evidence and the several errors in the rulings of the court below, to which we have adverted ; and the objections taken may be obviated on the new trial by an amendment, or perhaps by the plaintiff5s taking his new verdict, if one shall be obtained, upon the count to which no serious objection has been urged.
Exceptions sustained — new trial granted.