In order to constitute the appellant Smith a cosurety with the defendant L. R. Burch, there must have been a mutual understanding between the parties to that effect. Smith v. Smith, 16 N.C. 173; Cowan v. Baird, 77 N.C. 201; Bulkeley v. House, 62 Conn. 459; Thompson v. Sanders, 20 N.C. 541; Dawson v. Petway, 20 N.C. 531; Sayles v. Sims, 73 N.Y. 552; Sherman v. Black, 49 Vt. 198; 1 Brandt on Suretyship (2 Ed.), sec. 260. According to these authorities, it is plain that his Honor erred in holding the appellant as a cosurety with L. R. Burch.