The reason given in modern cases for the doctrine that a contract may be completed by mailing a letter of acceptance, or by dispatching a telegraphic acceptance, is that the use of the post-office or telegraph company has been authorized or indicated by the offeror as the means of communication, and that the acceptor is complying with a request made to him or authority given to him by the offeror in sending his acceptance in that way. If the offeror himself sends his offer by mail, this of itself implies authority to answer by the same channel of communication.11 Similarly, if an offer is sent by telegraph, authority to reply in the same way will be implied.12 If an offer is made orally, but is left open for subsequent acceptance, and the parties reside at a distance so that no subsequent personal meeting is apparently contemplated, an acceptance by mail would be authorized;13 and similar principles would govern the use of the telegraph,14 where the offerer has not himself made use of the medium of communication adopted by the offeree. The question whether that medium was authorized is one of fact; depending upon what would reasonably be expected by one in the position of the contracting parties, in view of prevailing business customs.
11 See cases supra, Sec. 80.
12 Williams v. Burdick, 63 Ore. 41,
126 Pac. 844; Perry v. Mt. Hope Iron
Co., 15 R. I. 380, 5 Atl. 632, 2 Am. St.
. Rep. 902; and see other cases cited in the preceding section.
13 Henthorn v. Fraser,  2 Ch. 27; cf. Scottish Am. Mtge. Co. v. Davis, 96 Tex. 504, 74 S. W. 17, 97 Am. St. Rep. 932.
14 In Perry v. Mt. Hope Iron Co., 15 R. I. 380, 5 Atl. 632, 2 Am. St. Rep. 902, an offer made in Boston in conversation was to "stand until the next day." The plaintiff telegraphed an acceptance from Providence. It was held that the contract was completed in Rhode Island. "If there be any question that the telegraph is a natural and ordinary mode of transmitting such an acceptance, that is a question of fact for the jury; but we are of opinion that if it be shown that the acceptance duly reached the defendant, the question of the mode, no mode having been specified is immaterial." See also Wilcox v. Oine, 70 Mich. 517, 38 N. W. S55; Tyng v. Converse, 180 Mich. 195, 146 N. W. 629; South Branch Cheese Co. v. American Butter & Cheese Co., 191 Mich. 507, 158 N. W. 158.