The words in the lease, "timber suitable for turpentine purposes," are not ambiguous in my opinion, and the expression means all the timber suitable at the date of the instrument for the purposes indicated. See Carter Elliott v. Williamson Co., 106 Ga. 280 (supra); McRae v.Stillwell, 111 Ga. 65 (36 S.E. 604, 55 L.R.A. 513);Martin v. Peddy, 120 Ga. 1079 (48 S.E. 420); Allison v.Wall, 121 Ga. 822 (6) (49 S.E. 831); McRae v. Smith,164 Ga. 23 (4) (137 S.E. 390). "Turpentine timber" has not only a provincial but also a general meaning. Ellis v. State,67 Ga. App. 821, 828 (21 S.E.2d 316). Even though it may be necessary to prove by parol testimony the usual size of timber suitable for turpentine purposes, this may be done without varying the terms of the writing, as the parties will be understood to have contracted with reference to the usual and customary rule in that particular. "But an attempt to limit the use of the property conveyed by parol proof involves an entirely distinct proposition," as was said by the Supreme Court in Shaw v. Fender, 138 Ga. 48, 52 (74 S.E. 792). It seems to me that to permit a party to a timber lease conveying the timber suitable for turpentine purposes to engraft upon the written contract by parol particular dimensions or specifications of timber that may be utilized is clearly adding to and varying a written contract, as prohibited by the Code, § 20-704. For these reasons the court should have sustained the demurrer to the petition. *Page 880