In case of doubt, an assignment is construed most strictly against the assignor,56 and generally the rules ordinarily applicable to the construction of contracts are applied.

Where an attempted assignment is ineffectual because the supposed obligation to which it related did not exist, the assignment will generally be construed as transferring any rights of the assignor relating to the same subject-matter as the supposed obligation.57 But the assignment of rights under a continuing contract does not imply an assignment of rights of action for previous breaches of the contract,58 though transferring a right to all payments becoming due in the future even for work done prior to the assignment.59 Similarly a sale of goods which the seller had previously bought with a warranty does not operate as an assignment of a right of action for damages for breach of the warranty.60 Frequently an assignment in terms absolute is intended to operate merely as security for a debt, and this may be shown by parol.61 Whether a right which it is attempted to assign or a duty which it is attempted to delegate is of so personal a character as to make the attempt unsuccessful, is a question of construction to be determined by the nature of the case and the presumed intention of the parties.62

54 See Currier v. Howard, 14 Gray, 511; Bullion v. Campbell, 27 Tex. 653.

55Young v. Upson, 115 Fed. 192; Re Macauley, 158 Fed. 322; Preston Nat. Bank v. George T. Smith Co., 84 Mich. 364, 47 N. W. 502.

56 Swan v. Warren, 138 Mass. 11.

57 Wetmore v. San Francisco, 44 Cal. 294; McCormick v. District of Columbia, 18 D. C. 534; Oneida Bank v. Ontario Bank, 21 N. Y. 490; cf.

Neugaas v. New Orleans, 43 Ia. Ann. 78, 9 So. 25.

58Regan Engine Co. v. Pacific Engine Co., 49 Fed. 68, 1 C. C. A. 169; Chicago Cheese Co. v. Fogg, 53 Fed. 72; Love v. VanEvery, 18 Mo. App. 196. See also Mullinax v. Lowry, 140 Mo. App. 42,124 S W. 572; Steele v. Brarier, 139 Mo. App. 319,123 S. W. 477.

59Chopin v. Pike, 184 Mass. 184, 68 N. E. 42.