delivered the opinion of the-court.
The Post-office Department is ¿a branch of the government, instituted for public convenience: The government of the United States has undertaken the business of conducting the transmission and distribution and delivery of all mail-matter. The government is the carrier of the mails. It carries them by the aid of agents it contracts with for this service. Contractors for carrying the mail are the agents of the government in the business undertaken by themT The sender of mail-matter has no contract with the carrier of the mail-bags, and does not commit his mail-matter to him, but to the government, which has undertaken to receive, carry, and deliver it. The contractor for carrying the mail is neither a common carrier nor a private carrier. He does not carry for individuals, nor receive any compensation from them. He has no knowledge of the mail-matter he carries, and no control over it, except to obey the instructions of the Post-office Department. Letters and packets - are inclosed in government mailbags, secured by locks provided by the government, and at all times subject to the supervision and control of the officers .and agents of the government in the Post-office Department, who may open the mail-bags and inspect the mail-matter they contain at will. Contractors for carrying the mail are instruments of government whereby it performs the function of transmitting mail-matter from place to place in the execution .of this part of its business.
Postmasters are necessary agents for the performance of the business of the Post-office Department, and those who carry ••the mail from place to place are equally necessary, and engaged in the business of the government.
A rider or driver employed by the contractor for carrying .the mails is an assistant about the business of the government. *81Although employed, and paid, and. liable to be discharged at. pleasure by the contractor, the rider or driver is not engaged, in the private service of the,contractor, but is employed in the-public service. United States v. Belew, 2 Brocken. 280.
A carrier of the mail is required by law to be of a certain age,, to take a prescribed oath, is exempted from militia and jury service, and is liable to certain penalties for violations of duty, as well as subject to be discharged from service by any postmaster, in a certain contingency. He is a subordinate agent of the government, whose employment is contemplated and provided for by the government in contracting to have the mail carried, lb.
Contractors for carrying the mail are responsible for .their own misfeasances, but not for those of their assistants. The assistants must answer for themselves. The only security for the safe transmission of packages by mail is the safeguards thrown around it by the regulations of the government, which announces that all valuables sent by mail shall be at the risk of the owner. All that the government promises, in case of loss of money or other valuables from the mail, is to endeavor to recover it and to punish the offender.
The duty of contractors to carry the mail is to carry it from place to place, subject to' the regulations of the post-office officials. Their obligation is to the government. They ánd. their assistants are agents of the government, and subject to. the rule of law applicable, in such cases. Story on Ag., secs. 313, 319 a, 321; Shear. & Redf. on Neg., sec. 177.
It is well settled that postmasters are not liable for losses-occasioned by the sub-agents, clerks, and servants employed under them, unless they are guilty of negligence in not selecting persons of suitable skill, or in not exercising a reasonable superintendence and vigilance over their conduct. Story on Ag., sec. 319 a; Story on Bail., sec. 463; 1 Am. Ld. Cas. 785; Schroyer v. Lynch, 8 Watts, 453; Wiggins v. Hathaway, 6 Barb. 632; Keenan v. Southworth, 110 Mass. 474; Whart. on Neg., sec. 292; Shear. & Redf. on Neg., sec. 180.
*82■ As remarked before, carrying the mail is just as necessary, and as much part of the business of the government, as the service rendered at the offices by postmasters; and those employed about carrying the mail are as much the agents of the government as are postmasters and their clerks and assistants. The true test of the character of a person is, not who appoints or pays or may dismiss him, but whether or not he is about a public employment or a private service. 1 Am. Ld. Cas. 621; Story on Ag\, sec. 319 et seq.
In Conwell v. Voorhees, 13 Ohio, 523, and Hutchins v. Brackett, 2 Fost. 252, it was decided that contractors for carrying the mail are not responsible to the owner of a letter containing money transmitted by mail and lost by the carelessness of the agent of the contractors carrying the mail. The rules applicable to 'agents of the public were applied. And although the doctrine, of these cases is criticised in Shearman and Redfield on Negligence (sec. 180), and has been disputed in Sawyer v. Corse, 17 Graft. 230, we adopt it as the better view.
■ In this case the money was stolen by the mail-carrier. As to that, he certainly was not the agent of the.contractors for whom he was riding, and, if they were liable for his acts within the scope of his employment, they were not liable for his willful wrongs and crimes. McGoy v. McKowen, 26 Miss. 487 ; New Orleans, Jackson <& Great Northern It. It. Go. v. Harrison, 48 Miss. 112; Foster v. Essex Bank, 17 Mass. 479 ; Wiggins v. Hathaway, 6 Barb. 632; Story on Ag\, sec. 309.
As the defendants in error were not liable for the money ** extracted ” from the mail by the carrier, they did not make themselves liable by giving their promissory note for it. It Is without consideration. . The compromise of doubtful rights is a sufficient consideration for a promise to pay money, but compromise implies mutual concession. Here there was none on the part of the payee of the note. His forbearance to sue for what he could not recover at law or in equity was not a sufficient consideration for the note. Newell v. Fisher, *8311 Smed. & M. 431; Sullivan v. Collins, 18 Iowa, 228; Palfrey v. Railroad Co., 4 Allen, 55; Allen v. Prater, 35 Ala. 169; Edwards v. Baugh, 11 Mee. & W. 641; Longridge v. Dorville, 5 Barn. & Ald. 117; 1 Pars. on Con. 440; Smith on Con. 157; 1 Add. on Con. 28, sec. 14; 1 Hill, on Con. 266, sec. 20.
Judgment affirmed.