delivered the opinion of the court.

The main question here (and indeed the only one of any difficulty,) is as to the propriety of the instruction given by the court in reference to the degree of care required of the captain in order to exempt him from liability under the statute against transporting a slave from one place to another, in this state, without the consent of the owner. The defendant insisted that such care as prudent men take in the management of their own affairs was all that was required; but the court instructed that “ the boat was liable if her master could have discovered and prevented the act by the ‘ strictest diligence.’ ”

In Vaughn v. Eaton, (9 Mo. 743,) which was a common *208law action of trespass against tbe captain of a boat for carrying off tbe plaintiff’s slave, the Circuit Court instructed that, in order to .charge the defendant, it was not necessary that he should have known that the boy was a slave, nor was it an excuse that he acted in .good faith and used reasonable diligence to guard against being imposed upon, and this judgment was affirmed here upon appeal. But in Price v. Thornton, (11 Mo. 140,) which was a common law action on the case against the owners of the boat for the master’s negligence in carrying off the plaintiff’s slave, under the belief that he was a freeman, there is an obiter dictum, of the judge who delivered the opinion of the court, to the effect, that, in order to bring the transaction within the act of 1840, (the original statute upon this subject, and which is similar in this particular to the existing statute,) the wrong must have been wilfully perpetrated. It seems however, in the present case, to have been assumed at the trial, that, although the transportation of the slave from Lexington to St. Louis was effected without the captain’s being aware of it, yet it was to be imputed to him as his act, so as to subject him to the penalty of the statute if he could have discovered and prevented it by the use of proper care in navigating his boat; and the point contested was, as to the degree of care required of him, whether the greatest care that it was possible to have used was necessary, or whether ordinary diligence was sufficient.

Thibaut, the eminent modern German jurist, in the general part of his System of Law, (ch. 3, div. 1, sect. 140, Lindley’s translation, 129,) distinguishes all transactions forbidden by law into four classes — accidental, when they result from natural causes, over which the human will hasjuo control; voluntary but not imputable, which the person might have prevented, but of the illegality of which he could not have been aware ; negligent, when performed neither with an intention of disobeying the law, nor with a morally wrong intention, but under such circumstances that a knowledge of the illegality of the act might have been attained ; and wilful, when committed by *209one who, having a knowledge of the law, disobeys it, and with a morally wrong intention. Without stopping to inquire whether this Glassification embraces every prohibited transaction, or indeed whether it is founded altogether upon distinctions that are recognized in our law, it is obvious that the acts included in the first class, not being the result of the human will, can not be imputed to any person as his act; and in re*-ference to the three remaining classes, we remark that, if the girl was transported here under such circumstances that it was utterly impossible for the captain to have known that she was on the boat, (if, indeed, such a state of circumstances can be imagined,) it ought not, we think, to be imputed to him as a violation of the statute; but yet we do not deem it necessary for this purpose that he should have been actually aware of the fact. It is sufficient, although he had no actual knowledge, that he could and would have known it, if he had navigated his boat with proper care to guard against such an occurrence. In ®ur opinion, the transportation of the girl on the boat, although not wilfully committed, must yet, in the construction of this statute, be imputed to the captain as his act, if he might have attained a knowledge of the fact by observing proper care. This construction is warranted by adjudged cases. An act passed in New Jersey before the abolition of slavery there provided that, “ if any one should be found guilty of conveying away a slave, whereby he should be lost to the owner, such person should pay to the owner the value of the slave lost and Gibbons v. Morse, (2 Halst. 253,) was an action founded on the statute against the owner of the ferry-boat between Eli-zabethtown and New York, to recover the penalty incurred by the defendant’s ferryman in taking the plaintiff’s slave across the river, and the owner of the ferry was held liable, although the wrongful act was not wilfully committed •; but at the same time, it was declared that it should have been otherwise, if the boy had entered the boat by stealth and so concealed himself that he eould not have been discovered in the ordinary management of the boat. This construction, too, is necessary in or*210der to make the statute effectual for the purpose for which it was enacted. If we confine the penalty to cases where the master wilfully transports a slave from place to place without the owner’s consent, and exclude from the statute the much larger class of eases where slaves are enabled by the carelessness of a boat’s officers to conceal themselves on board, and in this way effect their escape without the knowledge of the master of the boat, we shall render the statute almost a dead letter, instead of making it what it was intended to be, a substantial protection to the slave property of our citizens residing in the vicinity of our large rivers. And, although this is a penal statute, the construction we adopt is consistent with the established rules of law upon this subject. In Bae. Abr. (tit. “ Statute,” let. I, 10,) it is said that “the statute of Mal-bridge against committing waste is penal, yet it has been construed liberally,” and that “if the extending of a penal statute by an equitable construction, be more advantageous than prejudicial to the greater part of the people, it may by the rules of law be so extended.” It is also to be remarked, that the penalty here inflicted is given to- the injured party as a redress for the private injury sustained, and not imposed as a punishment for a public offence ; and although, as a genera! rule, to constitute a crime against the public, there must be both a vicious will and an unlawful act resulting from the vicious will, it is otherwise in reference to private injuries, where in most eases the intention is immaterial.

Coming down now to the matter discussed at the trial, and assuming that the alleged transportation of the slave occurred without the knowledge of the master of the boat, the question is, under what circumstances it ought nevertheless to be imputed to him as his act, so as to subject him to the penalty of the statute. In the construction of the statute, we have seen that the fact must be imputed to him, although he was not actually aware of it, if he might have known and avoided it by the use of proper care in the navigation of his boat, and we think that this proper eare is such as prudent men use in conducting *211their own affairs, hazardous to their own rights of property, in order to protect themselves from loss or injury. It is not sufficient that the master used such care as men of less than ordinary prudence take when engaged in their own affairs ; nor is it enough that he used such care even as prudent men are but too frequently satisfied with, when the danger is to the property of others, and not to their own ; nor will it be deemed sufficient that he used such care even as prudent captains generally use to guard against these escapes, if the care these persons take be not in the judgment of men in general proportionate to the probability of injury to others. Our law prohibits the captain of a boat from transporting a slave upon it without the owner’s consent, and whenever such an event occurs, it is imputable to the master of the boat, although not aware of it, if he gave occasion to it by the want of reasonable care in the navigation of his boat to prevent such an occurrence ; and, although the great practical difficulty is in determining what is sufficient care in the particular case, the proper standard for the government of the jury is, such care as thoughtful and prudent men, engaged in affairs equally hazardous to their own rights, generally take in order to prevent what they are doing from resulting in harm to themselves. In order to exempt the master from the penalty of the statute, the law does not exact from him the greatest possible diligence — all that we may imagine could have been done to have prevented the escape of the girl — but only such care as thoughtful and prudent persons would have taken in navigating a boat in the midst of a slave population, to prevent the escape of slaves upon it, if the property endangered had belonged to themselves, instead of belonging to others.

In Vaughn v. Eaton, it was held that the master of the boat was liable, although he used reasonable diligence to prevent being imposed upon; yet it is to be remarked, that the question there was as to a common law liability, and not in reference to the construction of a statute, and the act there complained of being the very act contemplated by the master of the boat, although he was not aware that the person transported as *212a passenger was a slave, and resulting in a direct and immediate injury to tbe plaintiff, constituted a good cause of action in trespass ; and the rule of the common law, laid down in Weaver v. Ward, (Hobart, 390,) was applicable to the case : “ No man shall be excused of a trespass except it may be adjudged utterly without his fault, as if a man by force take my hand and strike you ; or, if the plaintiff had run across the defendant’s piece, when it was discharging ; or it had otherwise appeared to the court that it had been inevitable, and that the defendant had committed no negligence to give occasion to the hurt.” Here, however, the question is as to the liability of the party to a statute penalty ; and the instruction having assumed that the removal of the slave was effected without the knowledge of the captain, we are not called upon to determine whether the rule that was applied in the case of Vaughn and Eaton would have been equally applicable in the case, if the suit had been for the penalty given by the statute, instead of for the common law redress. It may be, too, that there is a difference in the two classes of cases, even in the application of the statute to them, and that where the transportation of the person is the very act contemplated by the master of the boat, although he is not aware of its illegality, he can not escape the statute penalty unless he were utterly without any fault, or, in other words, unless it was impossible for him to have known that the person transported was a slave ; although it may be otherwise? where the negligence of the master, in navigating his boat, merely gives occasion to the injury by the facility it affords for the involuntary transportation of the slave upon the boat. If the master knowingly transport the person without being aware that he is a slave, the act, it may be, ought nevertheless to be imputed to him as his act within the meaning of the statute, unless it was utterly impossible for him to have been aware of the wrong he was committing, although only the ordinary care of prudent men may be required, in order to take the case out of the statute, where the slave gets upon the boat by stealth and is thus transported without the knowledge of the *213captain. In tbe one case it may be thought that, as the master contemplates the very act prohibited by the statute, he acts at his own peril, and must answer according to the statute for the act thus voluntarily committed if it turn out that he was imposed upon as to the condition of the person transported, although in the other case he would only be required to use that degree of care in the navigation of his boat that would become a prudent and thoughtful man under similar circumstances, in order to avoid the incurring of a similar injury to his own property. But however this may be, we confine our decision to the facts of the present case; and the view we have taken in reference to the liability of boat owners and masters under our statute, seems to be the same that was taken in South Carolina, in Ellis against Welch, (4 Rich. 468,) as to the liability of a ship’s captain at common law for having negligently given passage to the plaintiff’s slave from Charleston to Philadelphia under the belief that he was a free person. It was insisted that, although the captain acted in good faith, he was guilty of negligence in receiving the boy as a passenger upon the proof furnished that he was free, and the question was as to standard of care and caution that the law exacted of the captain on that occasion. The language of one part of the charge to the jury required “ the utmost care and diligence but the appellate court, taking the whole charge together, declared that this meant “ the utmost that, under like circumstances, the jury would exact from a prudent man engaged in a business hazardous to other people’s rights of property,” and the judgment was affirmed. And this is substantially the degree of care we require from the masters of boats, in order to exempt them from the penalty of the statute, when the transportation occurs without their knowledge. They are engaged in a business very hazardous to slave property, and it is not too much to exact of them, in the construction of this statute, that degree of care to prevent the escape of slaves on their boats that prudent men would take in conducting their own affairs, to guard against similar injuries to their own property, *214and that honest men feel themselves bound to take in reference' to the property of others. But the instruction of the court went beyond this ; the care exacted was “ the strictest diligence;” and although these words, when taken in connection with other instructions, might not import, as in the South Carolina ease, more than such care as prudent men take in the transaction of a hazardous business, yet there was nothing here to prevent them from being understood by the jury in their largest sense, so as to include every imaginable degree of care that would have tended to the discovery and prevention of the act complained of; and the refusal of the instruction asked by the defendant would seem to indicate that they were used by the court in this sense. We shall therefore reverse the judgment on this ground, that the case may be re-tried with a more perfect understanding of the law that we deem applicable to the case.

The other two points made in the case may be disposed of in a few words. The penalty of the statute is inflicted on the captain for his own act, and the boat is made responsible as an artificial person, for the better security of the party injured. And, although the boat was originally sued in the present case, yet under the provision of the 9th section of the act concerning boats and vessels, (R. C. 1845, p. 180,) the captain and his securities have been substituted as defendants in the place of the boat, which was thereby released, and the judgment to be recovered will be rendered against these substituted defendants, pursuant to the 21st section of the act, and we may therefore treat the case, in reference to the deposition and admissions of the captain, as if the suit had been originally instituted against him. Under this view of the matter, the captain’s deposition was properly excluded when offered in behalf of the defendants, and his declarations, properly admitted against him, not as part of the res gestae, but as the admissions of the real defendant, the party primarily liable for whatever may be recovered in this suit.

the judgment is reversed, and the cause remanded.