It is a general rule of law that where the promissor in suretyship puts the written contract in the hands of the principal, and authorizes him to fill the blanks, the surety will be bound by the acts of the principal, even though the principal disobeys instructions and fills in the blanks in a manner wholly unauthorized.5 The rule is one of the law of agency, and it is thought to be absolutely necessary, in order that third persons, dealing with agents, may be relieved from the chance of fraud and surprise, when they deal with agents apparently vested with authority.6 It is perhaps a broad application of the principle, that secret instructions of the principal have no force in binding third parties. In some cases the law gives the right to the beneficiary named in the contract to fill in certain blanks.

3 Bank of U. S. vs. Dandridge, 12 White, 64. 4 Fay vs. Richardson, 7 Pick., 91.

5 Cawley et al. vs. The People, 95

El., 249; Butler vs. U. S., 21 Wall., 272. 6 Fullerton vs. Sturgess, 4 Ohio St., 529.