Relying on various authorities giving legal definitions of a park as a place where the public may go for various kinds of recreation and amusement, including undeveloped land in its natural, primitive state, the City contends that, by not developing the 47.54 acres, but leaving it alone in its natural state without any active maintenance, it has "used" those acres and maintained them "for public park purposes," as required by the deed. See Lewis v. City of Fort Worth, 126 Tex. 458, 89 S.W.2d 975 (1936); Harris County v. Collin, 365 S.W.2d 187 (Tex.Civ.App.-Texarkana 1963, writ ref'd n.r.e.). Essentially, the City contends that, by not using the 47.54 acres but leaving it alone in its natural, primitive state, it has used and maintained it for public park purposes. But we must point out that, in this case, we are not guided by the legal, or even the commonly accepted, definition of a park.

A witness's opinion on an ultimate legal question is of no probative value. Dallas Railway & Terminal Company v. Gossett, 156 Tex. 252, 294 S.W.2d 377 (1956); Harris County v. Collin, 365 S.W.2d 187 (Tex.Civ.App. Texarkana 1963, writ ref'd n.r.e.). On further examination of the record, nothing is found to require affirmance of the judgment because of any presumption favoring its validity or upon grounds not briefed but supported by the record.

It is seen, however, that the affidavit establishes that affiant is in charge of the animal health program of Frio County and, thus, would be competent to testify that it was a Type II brucellosis control area. Obviously, a mere statement regarding cattle in the possession and control of Gluck would be of little probative force. See Harris County v. Collin, 365 S.W.2d 187 (Tex.Civ.App.— Texarkana 1963, writ ref'd n.r.e.). However, here the affidavit goes further and shows the basis for such conclusion.