One which has not accrued and which is dependent on the happening of some future event. Ilospes v. Car Co., 48 Minn. 174, 50 N. W. 1117, 15 L. R. A. 470, 31 Am. St. Rep. 637; Austin v. Saveland’s Estate, 77 Wis. 108. 45 N. W. 955; Downer v. Top- liff, 19 Vt. 399; Stichter v. Cox. 52 Neb. 532, 72 N. W. 848; Clark v. Winchell, 53 Vt. 408.