
202 Cal.App.2d 372 (1962)
RAYMOND A. PAYETTE, Plaintiff and Respondent,
v.
JOHN HENRY STERLE, Defendant and Appellant.
Civ. No. 25534. 
California Court of Appeals. Second Dist., Div. Four.  
Apr. 12, 1962.
 Parker, Stanbury, Reese & McGee and Daren T. Johnson for Defendant and Appellant.
 Oliver, Good & Sloan, John K. Sloan and Henry E. Kappler for Plaintiff and Respondent.
 JEFFERSON, J.
 Defendant appeals from a judgment for plaintiff in an action for personal injuries and property damage arising from an automobile collision. Since no question is raised as to the sufficiency of the evidence to support the judgment reference to the evidence introduced at the trial will be made only when pertinent to the issues on appeal.
 Defendant first contends the trial court erred in restricting *374 his cross-examination of plaintiff and a witness called by plaintiff.
 More than three years before the accident, which occurred on January 1, 1957, plaintiff, a world war veteran, suffered a nervous breakdown. He was treated at a veterans hospital from April until October of 1954, when he was released. At the trial, one factual issue concerned plaintiff's mental state prior to the accident since this was relevant to his earning ability and the extent to which his condition was aggravated by the accident.
 A witness called by plaintiff, one Bushnell, testified that he had seen plaintiff nearly every day from 1953 until the time of the accident. In later testimony the witness indicated that he meant he had seen plaintiff every day after plaintiff was released from the hospital in 1954. He stated that until plaintiff was involved in the accident "he was pretty well over his nervous condition" and "seemed to be getting along pretty well." Upon cross-examination defendant sought to inquire whether or not plaintiff, before April of 1954, had told the witness "he had a marked fear of the police and feared that the police were talking about him." Plaintiff's objection to the question was sustained. Thereupon, the judge excused the jury and the witness and admonished defendant's counsel that from such a reference to "police" the jury might infer improperly that plaintiff had a police record. Counsel conceded he was unable to establish that the witness had ever committed a felony. It further developed that counsel had not interviewed the witness but had learned of plaintiff's previous nervous breakdown and of certain symptoms plaintiff experienced during that illness and while under treatment at the hospital. Defendant's counsel asserted he had reviewed the Veterans' Administration records. He stated his intention to inquire of the witness whether plaintiff had ever told the witness that he felt "police were talking about him," and that "birds were swooping down on him." Counsel for plaintiff objected that these questions had prejudicial tendencies and should not be heard by the jury. The court agreed.
 For purposes of preserving the record for appeal counsel stipulated in effect that the questions on these subjects would be asked out of the presence of the jury and the witness, but just as if they were present; and, after plaintiff objected to each question, the court could rule on the objection. Counsel for defendant then asked in substance whether during the period from the beginning of 1954, through the end of 1957, *375 plaintiff told Bushnell (1) he had the feeling the police were talking about him; (2) he was having difficulty holding a job; (3) he felt a need to tell lies; (4) dogs barked at him and birds swooped down on him whenever he walked down the street; and (5) did the witness know that plaintiff was a mental patient who suffered from delusions in which he imagined everyone and everything was plotting against him? The court sustained the objections of counsel which were principally on the ground that the questions would be prejudicial to plaintiff.
 The objections were properly sustained. [1] The chief purpose of cross-examination is to assist the trier of fact in determining the weight to be given to testimony elicited on direct examination. This purpose is accomplished through testing the credibility, knowledge and recollection of the witness. (Sharp v. Hoffman, 79 Cal. 404, 408 [21 P. 846].) [2] The right of cross- examination is fundamental to due process of law, and, although scope of cross-examination in this state is limited to testimony received on direct examination (Code Civ. Proc.,  2048), there is a wide latitude allowed in testing credibility. (Newman v. Los Angeles Transit Lines, 120 Cal.App.2d 685, 691 [262 P.2d 95].) [3] Whether the probative value of a question on cross-examination is outweighed by its prejudicial effect is a matter for the determination of the trial court, and its ruling will not be overturned absent a manifest abuse of discretion.
 These inquiries pertained to symptoms of plaintiff's mental illness which had occurred prior to and during the time plaintiff was in the hospital. The witness had testified only concerning plaintiff's mental condition after he was released from the hospital. Therefore, the question as to whether there was a satisfactory recovery prior to the accident was partially obscured. Although defendant's counsel knew from the Veterans' Administration records that plaintiff had had such symptoms when in the hospital it was not shown that counsel had any basis for believing plaintiff had expressed these symptoms to the witness at any time or that he had any knowledge of them. From these facts it is apparent the trial court concluded that counsel was merely on a fishing expedition and that the harm which could result to the plaintiff outweighed any possible detriment to the defendant.
 [4] In sustaining the objections to these questions the court made it clear that it was not foreclosing defendant from asking *376 questions covering the same or similar subject matter but couched in a different or less prejudicial form. We cannot say under these circumstances that the court abused the broad discretion vested in it in the conduct of a trial.
 [5] While cross-examining plaintiff defendant again inquired upon the same subject matter, and plaintiff objected on substantially the same grounds recited above. The court sustained the objections whereupon defendant made an offer of proof in substance that since January 1, 1954, plaintiff suffered from symptoms of a mental disease; that he had hallucinations the police were talking about him; that dogs barked at him; that birds swooped down on him when he walked down the street, and that he felt a need to tell lies; and that as a result of these symptoms he had been unable to obtain employment except for approximately three months in the summer of 1957.
 The court sustained plaintiff's objections to the offer of proof. The offer of proof was material to the credibility of plaintiff and the witness Bushnell as well as to plaintiff's earning capacity before the accident and the aggravating effect of the accident upon plaintiff's preexisting nervous condition.
 We find that the action of the trial court in sustaining plaintiff's objections was not prejudicial in light of the evidence in the record as a whole.
 The substance of the testimony by plaintiff and Bushnell pertained to plaintiff's health after leaving the hospital in October 1954. The effect of the proof offered would have been to show, through Bushnell's apparent mistake as to the dates involved, that plaintiff was in the hospital at the time Bushnell testified that plaintiff was in good health. Since this fact had been explained on direct and redirect examination of Bushnell the adverse effect of this offer of proof upon his credibility would have been negligible, if any.
 Evidence introduced by plaintiff indicated that his only employment after his hospitalization, other than infrequent part time labor, was as a janitor in Sequoia National Park in the summer of 1957. Upon cross-examination, prior to the offer of proof, plaintiff admitted that after his release from the hospital in 1954 he was unable to hold a job. To this extent the offer of proof was substantially cumulative of testimony already received by the trial court through the same witness and could therefore be properly rejected. (Tossman v. Newman, 37 Cal.2d 522, 526 [233 P.2d 1].) *377
 On cross-examination, prior to the offer of proof, plaintiff was also asked if, from the beginning of his last hospitalization up to the time of trial, he had experienced hallucinations in which he imagined dogs were barking at him when he went down the street and birds were swooping at him. His answer was: "Absolutely not." Further, there was no evidence that plaintiff had seen a psychiatrist or a neurologist subsequent to the accident, and the testimony of two doctors, called by plaintiff and defendant respectively, indicated plaintiff had no abnormal mental state after the accident. This court will not speculate on what additional information could have been obtained by further examination on this point. From our review of the testimony on these issues it cannot be said that there was a reasonable probability that the facts sought to be elicited would have affected the result.
 Defendant next contends the trial court erred in refusing to admit into evidence the Veterans' Administration records as to plaintiff's preexisting "nervous disorder."
 [6] During the trial the plaintiff introduced a photocopy of a letter sent to plaintiff by the Veterans' Administration entitled "Award of Disability Compensation or Pension" which he had acquired from the claims portion of the Veterans' Administration file. Subsequently, defendant, who had caused the file to be brought to court through two subpoenas duces tecum, attempted to introduce the rest of the file. Plaintiff objected to the admission of the file on the ground that the information was privileged under a United States Code provision pertaining to Veterans' Administration hospitals. Defendant countered with the argument asserted on this appeal that the privilege was waived when part of the file was introduced during plaintiff's case in chief. The court ruled that the privilege was not waived by the introduction of the photocopy of the letter.
 Although these records might have been admissible under state law they were properly excluded because of the federal law applicable in the instant case.
 Section 3301 of 38 United States Code provides in part: "All files, records, reports, and other papers and documents pertaining to any claim under any of the laws administered by the Veterans' Administration shall be confidential and privileged, and no disclosure thereof shall be made except as follows: ... (5) In any suit or other judicial proceeding when in the judgment of the administrator such disclosure is deemed necessary and proper." *378
 Defendant could have sought to introduce the record into evidence through compliance with subdivision five of the pertinent federal code section and the regulations promulgated with respect thereto.  [fn. 1] Although defendant subpoenaed the records there was no showing that he had secured the federal administrator's approval and, in fact, the transcript indicates the administrator did not approve. Plaintiff seasonably and properly objected. Under these circumstances we hold that the trial judge properly sustained the objection to the introduction of the remainder of the file. The fact that plaintiff introduced a document from the claims portion of the same file could have been made known in defendant's affidavit to the Veterans' Administration had he sought to proceed under the federal regulations to show the administrator that "disclosure of records [was] necessary and proper to prevent fraud or other injustice." (38 C.F.R. 1.511(c).)
 Lastly, defendant claims the court erred in giving an instruction on the prima facie speed limit. [7] The court instructed the jury: "The prima facie speed limit at the place where the accident occurred was 25 miles per hour. This fact is one to be considered by you, together with all of the other evidence, in determining whether or not the defendant was negligent. ..."
 Defendant does not question the propriety of the instruction but contends there was no proof that the accident occurred in a business or residential district where the speed limit would be 25 miles per hour, and therefore, the instruction offered by plaintiff was erroneously given by the court. This instruction was properly given in the instant case if there was proof of the facts specified in Vehicle Code sections 235 and 240 establishing the area as a business district. *379
 The only testimony on this issue was provided by a police officer who testified in substance that the buildings in the area along Eighth Street were "mostly business structures" in addition to hotels and apartment houses and that the area was built up all the way along the street. In response to counsel's question as to whether the area was a "business district," he replied "Strictly business."
 The officer's testimony on this subject was received without objection. Defendant's counsel did not offer evidence to controvert it. Under these circumstances the officer's testimony provided a sufficient basis for the giving of the instruction.
 The judgment is affirmed.
 Burke, P. J., and Balthis, J., concurred.
NOTES
[fn. 1]  1. 38 Code of Federal Regulations 1.511(c) (1956) states: "Where copies of documents or records are requested by the process of any State or municipal court, ... the process when presented must be accompanied either by authority from the claimant concerned to comply therewith or by an affidavit of the attorney of the party securing the same, setting forth the character of the pending suit, the purpose for which the documents or records sought are to be used as evidence, and, if adversely to the claimant, information from which it may be determined whether the furnishing of the records sought is necessary to prevent the perpetration of fraud or other injustice. ... If it appears by the process or otherwise that the records are to be used adversely to the claimant, the averments contained in the affidavits shall be considered in connection with the facts shown by the claimant's file, and, if such consideration shows the disclosure of the records is necessary and proper to prevent a fraud or other injustice, the records requested shall be produced." (Emphasis added.)
