An offer may adopt in part the terms of another instrument, and may thus be the basis of a valid contract; although, without such reference to such contract, the offer itself would have been incomplete.1 An offer referring to a previous contract for the price is complete, though the price is omitted from such offer.2 A contract may be definite although certain terms are omitted, if a contract to be made thereafter between one of the parties and a third party is adopted in advance to supply such terms; such as a building contract,3 or an insurance contract,4 or a contract to pay certain attorneys as much as either of two other attorneys receives for his services in the case.5 The fact that a contract provides that certain work is to be done "in accordance with plans and specifications to be furnished," does not render such contract indefinite, if, in fact,

18 Price v. Wiesner, 83 Kan. 343, 31 L. R. A. (N.S.) 927, 111 Ac. 430; Price v. Stipek, 30 Mont. 426, 104 Ac. 105. [It would seem as though the court were unwilling to enforce such contracts because they were unfair and oppressive: but it preferred to assign as a reason for refusing to enforce such contracts the fact that they were indefinite and uncertain.]

19 Christie v. Patton, 148 Ala. 324, 42 So. 614.

20 Oliver Typewriter Co. v. Huffman, 65 W. Va. 51, 63 S. E. 1086.

21 Oliver Typewriter Co. v. Huffman, 65 W. Va. 51, 63 S. E. 1086.

1 American-Pacific Const. Co. v. Modern Steel Structural Co., 211 Fed. 840, 128 C. C. A. 375; Henderson v. Spratlen, 44 Colo. 278, 08 Ac. 14; Walsh v. Myers, 02 Wis. 307, 66 N. W. 250.

2 Walsh v. Myers, 02 Wis. 307, 66 N. W. 250. (An order for ten thousand cans of lye to be furnished "as heretofore.")

3 Blaney v. Hoke, 14 O. S. 292.

4 Tower v. Grocers', etc., Co., 150 Pa. St. 106, 28 Atl. 220.

5 Lungerhausen v. Crittenden, 103 Mich. 173, 61 N. W. 270.

such plans and specifications were prepared and were attached to such contract when it was executed.6

A term which is not fixed in a contract may be made sufficiently certain by reference to extrinsic facts which fix it.7 A contract to support a person as long as she suffered from certain injuries; 8 a contract to pay fifty cents per thousand feet for all pine trees exceeding a certain size, upon a certain tract of land, payment to be made from time to time as the trees were cut;9 a contract by which A agrees to advance to B money enough to pay B's employes;10 a contract by which the father of an illegitimate child agrees to make such child equal with his other children in the distribution of his estate;11 a contract to manufacture staves as long as the parties can secure "sufficient timber for that purpose in the locality of the mill";12 a contract adjusting the rights of parties in a tract of land which described such land by its area, the county in which it is located, the stream on which it is located, and the fact that the parties to the contract had occupied it,13 and a contract to furnish free telephone service to the public officers of a city as long as the telephone company maintains a telephone exchange in that city,14 are each sufficiently complete. A contract for furnishing a certain quantity of structural iron by weight, which gives the dimensions of the building for which it is to be furnished, is not rendered invalid by the fact that the exact details according to which the iron was to be furnished were to be given in certain drawings to be approved by the architect of the property owner, since it was clear that such buildings were to be based upon the general plans already prepared by the architect.15 A contract to pay an amount equal to that expended by the promisee, if such amount, though not then ascertained, is ascertainable from vouchers and bills, is complete.16 If a contract contains an express reference to another writing as part thereof, such other writing must be put in evidence in order to prove the terms of the contract.17

6 Cleveland, C. C. & St. L. Ry. Co. v. Moore, 170 Ind. 328, 82 N. E. 52 [rehearing denied (1908), Cleveland, C. C. & St. L. Ry. Co. v. Moore, 84 N. E. 540].

7 Henderson v. Spratlen, 44 Colo. 278, 98 Ac. 14; Kent v. Lumber Co., 122 La. 1046, 48 So. 451.

8 Henderson v. Spratlen, 44 Colo. 278, 98 Ac. 14.

9 Kent v. Lumber Co., 122 La. 1046, 48 So. 451.

10 Pugh v. Jackson, 154 Ky. 649, 157 S. W. 1082 [rehearing denied in Pugh v. Jackson, 154 Ky. 772,159 S. W. 600].

11 Lewis v. Creech's Admr., 162 Ky. 763, 173 S. W. 133.

12 Alderton v. Williams, 139 Mich. 296, 102 N. W. 753.

13 Waring v. Loomis, 35 Wash. 85, 76 Ac. 510.

14 City of Superior v. Douglas County Telephone Co., 141 Wis. 363, 122 N. W. 1023.

15 American-Pacific Construction Co. v. Modern Steel Structural Co., 211 Fed. 849, 128 C. C. A. 375.

16 Wehner v. Bauer, 160 Fed. 240.

Reference to an extrinsic instrument may not be sufficient to make the contract definite enough to be enforced, if such extrinsic instrument does not exist or if its terms can not be ascertained.18 A contract by which A agrees to lease to B certain realty for ninety-nine years "on the usual terms as applied to a ninety-nine year lease," can not be enforced specifically in equity if it is shown that there is no general or usual form for a ninety-nine year lease in use in the city where such realty is located.19