The opinion of the court was delivered by

The first exception, taken by the plaintiff, was to the admission of the deputy sheriff, Denison, as a witness for the defendant, after being discharged from all liability to him for the *22consequences of the neglect, or misfeasance, complained of. We deem it too well settled, that a deputy, when thus discharged, is admissible as a witness for his principal, to be now questioned. The decision to this effect in Ordway v. Bacon, 14 Vt. 378, was in accordance with long and uniform practice in this state. Had it appeared, that the deputy had incurred expenses in defending the suit, which were dependent upon its result for their reimbursement, the question would doubtless have deserved a different consideration ; but as nothing of that kind was disclosed, the witness was correctly admitted.

Objection was also taken, and is still urged, to the admission of the judgment debtor, Steele, as a witness for the defendant. The ground of this objection is, that the witness stood in a condition to be liable over to the defendant, at least for the costs of this action, if the plaintiff recovered. But it should be borne in mind, that his promise to return from New Hampshire was not made to the defendant, but to Denison, who was afterwards discharged from all accountability. Besides, if at the time of receiving the promise it was the official duty of Denison, as the plaintiff insists,.to arrest and commit Steele without delay, the indulgence, for which the promise was given, being clearly for ease and favor, was inconsistent with such official duty, and the promise was therefore void in law. Stevens v. Webb, 2 Vt. 344. There was no valid objection to the competency of the witness.-

It is farther contended, that the question of reasonable diligence in this case was a question of law for the court exclusively to decide; and that the judge erred in declining to instruct the jury, that the failure to arrest and commit the debtor, on or before the 24th day of April, was such a want of diligence in the officer as entitled the plaintiff to recover. We think, however, that the judge was right in treating the question of diligence as a mixed question of law and fact. It has never, to my knowledge, been regarded otherwise in any case of this description. Indeed, it is obvious that no rule can justly be prescribed, fixing the precise time within which the successive duties of the officer shall be performed in these cases, since the proper and requisite time must depend upon such numerous and ever varying circumstances. We have an illustration of this in the present case, which involved a complica*23tion of matters to be considered, many of them not even stated to us as facts proved, but only such as the evidence tended to prove. It was therefore sufficient for the judge to advance those propositions in regard to the officer’s duty, which, if honestly and sensibly •applied by the jury to the case on trial, would lead them to a just result. And as such a charge was given, holding the officer to a very strict measure of diligence, it was all that the plaintiff could legally require.

Judgment of county court affirmed.