delivered the opinion of the Court:

It appears generally that the building was completed according to the plans and specifications, and that the construction was satisfactory to the defendants.

The question was not, then, as to the particular qualifications of the plaintiff for the duties of a superintendent of construction, but as to the reasonable value of his services. As the plaintiff was not a regular superintendent of building construction, but was engaged in the particular case while regularly performing his clerical duties for another, which occupied the bulk of every day that the construction was under way, and gave but a small part of his time each day to the matter of superintendence, it seems to us material that the jury should be *46informed as to the salary he was receiving for his regular duties. Evidence on plaintiff’s behalf tended to show that it was customary to pay a superintendent a percentage of the cost of the building. "On the other hand, testimony tended to show that such services, when daily performed, were generally paid for by the-day at a price ranging from $5 to $6. The jury did not allow the whole of the claim based on the percentage rate, but considerably less. They were not bound to accept the estimate of value fixed by witnesses, but had the right, which they evidently exercised, of determining the weight and force of all the evidence by their own general knowledge of the subject of inquiry.. Head v. Hargrave, 105 U. S. 45, 49, 26 L. ed. 1028, 1030. Estimating the six months of construction at 180 days, theverdiet for $900 may have been arrived at by allowing plaintiff $5 per day, without adding thereto the $100 which he paid to-attorney, or the $50 of incidental expenses. "While the jury were not bound to estimate the value of the services per day or per month by the salary received by plaintiff, yet, as defendants knew that he was performing services for them in addition to-his regular employment by Bradley, who was their collectings agent, it was competent evidence for the consideration of the-jury in determining the amount of their liability for his services. It is to be remembered that plaintiff did not claim to-have any special qualifications as a building inspector. He did not pursue that occupation, and had no knowledge, from experience, of the value of an inspector’s services. His regular-occupation was clerical, and the value of his time as a clerk was determined by his salary. Moreover, the architect was paid, to-his knowledge, $600 for similar services of superintendence during the same period, and this he thought fair to allow as a credit upon his own demand. Strange to say, the architect was not called as a witness by either party.

Plaintiff, who failed to assign any particular ground of objection to the competency or relevancy of the evidence sought to-be elicited, now contends that it was the duty of the defendants to point out specifically, not only what were the grounds upon which they claimed the competency of this evidence, but also to-*47state what they expected to prove by the witnesses. It is true that, where evidence is generally incompetent or irrelevant, it is the duty of the party seeking to introduce it to state special grounds constituting it an exception to the general rule, so that the court may be fully informed in regard to the question which he is called upon to decide, as well as that opposing counsel may not be taken by surprise. This is not the case here, however. Plaintiff had testified to the other employment, and, of course, knew the amount of his salary. The relevancy of the question did not depend upon the amount of that salary, but its force and effect only as bearing on the question of the value of his services, which was for the jury to consider. Under the circumstances of the case, we think that the exception may be considered, and that the evidence was competent. The conditions are quite different from those of the cases relied on by plaintiff. De Forest v. United States, 11 App. D. C. 458, 460; Turner v. American Security & T. Co. 29 App. D. C. 460, 468. In the first of those cases, the party assigning error upon the admission of the testimony stated no ground of his objection. It was said that specific grounds of objection are required, so that they may appear on the record, and in order that the other party may have an opportunity to obviate them. Moreover, it was said: “Nor are we at all certain, from the circumstances of the record, that the testimony here in question was absolutely inadmissible.” See also Washington Gaslight Co. v. Poore, 3 App. D. C. 121, 135. In Turner v. American Security & T. Co. supra, the trial court refused the offer of a witness to prove his opinion in respect of the competency of a testator. The introducer failed, however, to state what the opinion was that he wished an opportunity to introduce. Under the circumstances of that case it was held that it was the duty of the party to show what was that opinion, so that the appellate court might be able to determine whether the exclusion was in fact prejudicial.

The application of this strict rule necessarily depends upon the' apparent character of the evidence and the circumstances of the case. When incompetency and irrelevancy are clear and *48apparently insurmountable, it may not be necessary always to state tbe objections specifically. Nor where the competency or relevancy are alike plain, from all the circumstances, is it necessary to assign specific grounds of admissibility.

For substantially the same reasons, above given, we are of •the opinion that there was error in sustaining objections to two of the questions propounded, to the witness Richardson. These were: (1) “To earn the full compensation of a building superintendent how much time should he spend on the building?” (2) “What, in your opinion, would be the reasonable -compensation of a superintendent of a building who should spend from half an hour to one hour a day upon a building?” Testimony of a competent person, as this witness had shown himself to be, is admissible on the subject of values of property, professional or personal services, and the like, where the same is the subject-matter of controversy. The matter to be determined here was the value of plaintiff’s services during a -certain period. Two grounds of estimating the same were before the jury, namely, the percentage and the per diem, basis. It was for the jury to adopt either, and the amount of the verdict would seem to indicate the adoption of the latter. While they were not bound to adopt the testimony of a witness familiar with the necessary character and the value of such services, nevertheless the party was entitled to have it submitted to them as proper aid to the fair and intelligent consideration of the point at issue.

It was not error to refuse to permit evidence as to the necessary qualifications of a building superintendent. There was no question of competency' or incompetency in the case. The work had been completed to the satisfaction of the defendants, whether due to the services of the plaintiff or not. If they were satisfied to permit him to act as superintendent, and had no complaint to make of incompetency, they could not be heard to urge his want of qualification as a ground for refusing to pay for his services.

The form of the second question to the witness Holdep. was objectionable. It should have been in the form of the one to *49Richardson, as to the reasonable value of such services as had been rendered by the plaintiff.

We see no objection to the special instruction excepted to.

For the reasons assigned, the judgment will be reversed, with costs, and the case remanded for a new trial. Reversed.