delivered the opinion of the court.
The only question for our determination is presented by the assignment of error, predicated upon the giving of the instruction above quoted.
Counsel for the respective parties have devoted most of their briefs and argument to the discussion of the question of the adequacy of an oral authorization to confer the power *597to fill blanks in. a sealed instrument after the same is signed and before delivery. The pertinency of this contention to this case is not readily discernible, since the instrument sued on is not a sealed instrument but is a parol contract, and of a class to which the strict and technical doctrine relied on by counsel for appellees is not applicable. The court below tried the case upon the theory that such authority could be conferred orally, and admitted evidence upon the question whether oral authority was given to Clark by Egan and Brown to fill the blanks with the description and value of the property attached; and submitted to the jury as the fact upon which a recovery depended, whether such authority was expressly given; hence, the pertinent inquiry is, was it error to take from the jury the consideration and decision of the question, whether, under all the facts and circumstances attending the signing and delivery of the paper to Clark in its then condition, the authority to fill the blanks therein was conferred upon him by implication ?
In the case of Inhabitants of South Berwick v. Huntress, 53 Me. 89, Kent, J., in discussing an instruction embodying in substance the law applicable to this case, said:
“We think that when a party signs a bond and delivers it to another, not stipulating or expecting that the paper will be returned or afterwards exhibited to him, but be delivered to the obligee when perfected, and when he so delivers it there are blanks in it to be filled up before it can be perfected, and he knows the fact, those blanks may be filled out without any further knowledge or assent on his part.”
And also on page 96, “ It is after all a mere question of assent. Now, consent may be implied as well as expressed, and when fairly and legally inferred it is actual and effective consent, as much so as when direct authority is shown by parol.”
The supreme court of the United States has announced the same principle in several cases, notably that of Drury v. Foster, 2 Wallace, 24. Therein the court say:
“We agree that by signing, and acknowledging the deed *598in blank, and delivering the same to an agent, with an express or implied authority to fill up the blank and perfect the conveyance — its validity could not well be controverted.”
In the ease of the State of Minnesota v. Young, 23 Minn. 551, the court in discussing the implied authority of the board of county commissioners to fill the penalty in an official bond, no express authority being given, says:
“ Such authority may be implied from circumstances. It may be implied from the facts proved, when these facts all taken together and fairly considered justify the inference.” See also, White v. Duggan, 140 Mass. 18; Smith v. Crocker, 5 Mass. 537; Bank of Commonwealth v. McChord, 4 Dana, 191; McCormick v. Bay City, 23 Mich. 457; Bartlett v. Board of Education, 59 Ill. 364; City of Chicago v. Gage, 95 Ill. 593.
Numerous other cases might be cited in support of the rule that authority to fill blanks in such an instrument may be implied, and that when .fairly inferable from the conduct of the parties, and circumstances surrounding the transaction, is as effectually given as if expressly conferred. Many of these decisions are put upon the doctrine of estoppel in pais, ostensible authority being the equivalent of actual authority. It certainly is consonant with justice and fairness that when a person as a surety signs an incomplete undertaking, and places the same in the hands of another to use for a particular purpose, and with ostensible authority to fill in any needed matter to make the same effective, and the same is accepted in its completed form by the obligee without negligence on his part, that such' surety ought to be estopped from controverting its validity to the prejudice of such obligee; and we think that the facts in this case most strongly invoke the application of this rule. The blank, as presented to Egan and Brown for their signature, contained a printed condition that fully advised them of the extent of the obligation they were assuming; the insertion of the penalty did not affect the extent of such obligation. The printed recitals in the paper as presented were to the effect that certain property of their principal had been attached, and the condition, and essential *599portion of the contract, in terms provided that in consideration of the releasing of said property they undertook and promised that if judgment was obtained in the attachment suit, and the attachment sustained, that on demand the3r would re-deliver such property, and in default of delivery they would pay the full value of the property so released. They were bound to know the contents of the paper they signed, and cannot evade liabil^ by pleading want of such knowledge. To avail themselves of such a defense it must appear that they were prevented from reading the paper by some trick or artifice of the obligee. Johnston v. Patterson, 114 Pa. St. 398. They were also bound to know whether there were blanks that must be filled to accomplish the purpose for which such undertaking was intended. They are presumed to have known the law, and knew that to accomplish the purpose of their principal it was necessary for him to procure an undertaking in compliance with the statute. With this knowledge they signed the undertaking and placed it in his agent’s hands, as we have seen, with implied authority to fill the blanks, and otherwise perfect it for the purpose of releasing the attached property. Counsel for appellees place stress upon the fact that Clark, the attorney of Brasher, made the addition, and that the appellees, by delivering the bond to him when signed, conferred no authority upon him to do so. This claim is not tenable. He was their agent as well as the agent of the principal. Willis v. Rivers, 80 Ga. 556.
We think the court erred in giving the instruction complained of. The evidence clearly establishes the fact that the appellees conferred the power upon their principal and upon his attorney, Clark, to fill in the specific description of the property attached, and its value, if that was necessary to make the undertaking effective. It is unnecessary to decide whether the undertaking as signed was not sufficient before the additions were made therein. And, since we are of the opinion that upon the undisputed facts the appellants were entitled to recover, the judgment is reversed and cause remanded, with directions to assess damages in favor of appellants.
Reversed.