in the letter as received by him. In this case, if no more
it is clear that B. cannot hold A. bound by the contract
essed in the documents in their existing state. In order that
. may be bound it must be shown that the alteration was made
y his authority, which may be proved, certainly by evidence of
dent authority given by him to the person by whom the
alteration was made, and, possibly, by evidence of ratification.
ut this would seem to depend upon whether the falsifier should
e regarded as having purported to act as agent for A. in making
ne alteration: see Keighley, Maxsted «& Co. v. Durant (1). It is
also that B. would not be bound by the offer as written by A,
he were estopped from denying the alteration. And, since
mtract must be mutual, it would seem that, as B. could not
A. upon the contract contained in the altered document, so
also A. could not sue B. upon that contract. If this is the correct
, there could not in such a case be any binding contract at
If, however, A. could sue B., and did sue him, upon the
act evidenced by his letter of acceptance, it is clear that
would be bound by the terms of the letter which B. actually
wed. Another case may be put, which in principle seems
tical. A writes a letter to B,, making an offer of a con-
t, and hands it to C. for delivery to B. C., instead of
ering the document written by A., delivers a different
ment containing a different offer, which B., by letter to A.,
pts. Here again, if A. can sue B. on the contract evi-
iced by the substituted letter, it must be either on the ground
that C. was A's agent to make the substitution, or on the
ind that A. by suing ratifies C.'s act. This latter view
accepted by the Supreme Court of Maine in the case
Richardson v. Maine Insurance Co. (2) cited with approval
by the Supreme Court of the United States in New York
life Assurance Co. v. Fletcher (3). If, however, B. is to be
held bound to the terms of A.'s genuine offer, it must be on the
ound that he is estopped from denying that ©. made the
titution. Such an estoppel must arise from his own conduct,
dcan only arise if he has failed in some duty which he owed to
in the particular transaction. See Farquharson Bros. & Oo. v.