of the Supreme Court of the District of Columbia, who sat with the court in the hearing of this cause in the absence of Mr. Chief Justice Alvey, delivered the opinion of the Court:

The chief question for consideration is whether or not the appellant’s pleas set up a good defense to the action.

Under his first three pleas, the appellant contends that he has a two-fold defense to the action:

First. That the delivery of the sealed instrument to the appellee was conditional.

Second. That the condition upon which the sealed instrument was delivered constitutes a valid and binding collateral agreement between the parties, the terms of which have not been complied with by the appellee.

1. While it is true that there can be a conditional delivery of an instrument, even though it be a sealed one, and a failure of the condition will prevent the instrument from becoming operative, it is equally true that, in the case of a sealed instrument, the delivery, if conditional, cannot be made to a party to it with*521out waiving the benefit of the condition, unless the condition appears upon the face of the instrument itself. Moss v. Riddle, 5 Cranch, 351, 3 L. ed. 123, Chief Justice Marshall; Newman v. Baker, 10 App. D. C. 187: In the latter case, this court said:

“The rule is that a deed or any other sealed instrument cannot be delivered to the grantee or obligee himself as an escrow, to take effect upon a condition not appearing on the face of the deed or other sealed instrument. The delivery must be to a stranger; otherwise the deed or other sealed instrument becomes absolute at law” (p. 197).

There are, of course, eases in which, although sealed instruments have gotten into the possession of a party to them, they are held never to have taken effect-; but these are cases in which the possession by the party himself was secured either wrongfully, accidentally, or inadvertently, and not where a delivery was intentionally made to a party himself (with a reserved condition, however, understood between them but not appearing upon the instrument). Calhoun County v. American Emigrant Co. 93 U. S. 127, 23 L. ed. 826.

The case of Hartford F. Ins. Co. v. Wilson, 187 U. S. 467, 47 L. ed. 261, 23 Sup. Ct. Rep. 189, cited by the appellant, was one in which, in the first place, there never was any intentional delivery (conditional or otherwise) to a party himself, and, in the second place, the instrument was not a sealed one. In the case of Burke v. Dulaney, 153 U. S. 228, 38 L. ed. 698, 14 Sup. Ct. Rep. 816, also cited by the appellant, the instrument was simply a promissory note; and, in the case of Donaldson v. Uhlfelder, 21 App. D. C. 489, the instrument was a signed lease, and not a sealed one..

The case of Clark v. Gifford, 10 Wend. 311, cited by the appellant, did. it is true, involve a sealed instrument, but the delivery was made to a third person. And in the case of Leppoc v. National Union Bank, 32 Md. 136, the sealed instrument involved was never actually delivered to, or accepted by, a party to it at all; it was simply acknowledged and recorded by the grantor and retained by him to await an expected development which did not take place.

*5222. The next inquiry is as to whether the condition, although invalid as affecting the delivery of the sealed instrument to a party to it, is valid as a collateral agreement between the parties. It is to be observed that the instrument here sued upon is complete on its face, unambiguous in its terms, and under seal, and contains an unconditional promise to pay the sum sued for upon the happening of an event which, it is admitted, has occurred. Applying, therefore, the doctrine laid down by the Supreme Court of the United States in the case of Seitz v. Brewers' Refrigerating Mach. Co. 141 U. S. 510, 35 L. ed. 837, 12 Sup. Ct. Rep. 46, as follows: “Undoubtedly the existence of a separate oral agreement as to any matter on which a written contract is silent, and which is not inconsistent with its terms, may be proved by parol, if, under the circumstances of the particular ease, it may properly be inferred that the parties did not intend the written paper to be a complete and final statement of the whole of the transaction between them. But such an agreement must not only be collateral, but must relate to a subject distinct from that to which the written contract applies; that is, it must not be so closely connected with the principal transaction as to form part and parcel of it. And when the writing itself upon its face is couched in such terms as import a complete legal obligation, without any uncertainty as to the object or extent of the-engagement, it is conclusively presumed that the whole engagement of the parties, and the extent and manner of their undertaking, was reduced to writing,” — it is manifest that the condition set up by the appellant is no more sustainable as a collateral agreement than it is as a qualification upon the delivery of the sealed instrument itself.

3. The next question is whether or not the appellant’s fourth plea’sets up facts which constitute a waiver on the part of the appellee of performance on the part of the appellant under the terms of the bond. The appellant sets up in this fourth plea that he offered to protect the property from sale under said deed of trust by substituting therefor a new deed of trust sufficient in amount to discharge said existing deed of trust, together with costs, charges, and expenses, and tendered himself ready and *523willing to do and perform everything necessary on his part to be done and performed, but that the appellee refused to permit the appellant to so protect the property against sale, for the reason that he himself (the appellee) intended to protect his interest in the property, and thereupon agreed, in consideration of the premises, to excuse the appellant from protecting the property.

It is to be observed that nowhere in this plea is there a single allegation that the appellee ever agreed to release the appellant from his obligation under the bond, but simply that he agreed to excuse him from doing something which he was not obligated to do at all, and which had nothing whatever to do with the bond, namely, from protecting the property against sale under the deed of trust. It cannot, therefore, be said that the appellee has, of This own accord, waived performance of the terms of the bond. Nor is there anything in the plea which can be construed as setting up a waiver by estoppel, or, in other words, that the appellant has, by any act of the appellee, been actually misled to his detriment. The appellant, it is true, complains in his plea that the appellee permitted the property to be sold under the deed of trust, although he had agreed not to do so; but, in the first place, such agreement on the part of the appellee (if it were ever made) was not supported by any consideration, and, in the second place, it is not alleged in the plea that at the time the appellee permitted the property to be sold under the deed of trust the appellant was not aware of it. A waiver to be valid and binding must be supported either by a consideration or by estoppel.

As is well said in appellee’s brief, the bond sued on imposed no duty on the appellee to protect the property from sale under the deed of trust, and it likewise imposed no duty on him to permit the appellant to protect it from sale.

4. The only remaining question is whether the court below erred in refusing to permit the damages suffered by the plaintiff (the appellee here) to be assessed by a jury. The suit was brought for a liquidated sum of money due under the express terms of a sealed instrument or bond. The declaration set out the condition of the bond, the breach of the condition, and the *524amount of money due and sought to- be recovered under the very terms of the bond itself. The case is quite different from that of an action of covenant sounding in damages, where the amount due the plaintiff is uncertain and depends upon matters dehors the record, and hence requiring proof aliunde for its ascertainment. Here the amount sought to be recovered “is fixed and ascertained by the instrument itself * * * and thus proves itself.” Clark v. Harmer, 5 App. D. C. 115; Simonton v. Winter, 5 Pet. 149, 8 L. ed. 18.

The appellant’s pleas being properly held insufficient, the court below was justified in entering judgment in favor of the appellee for this liquidated sum of money without the useless interposition of a jury.

Finding no error in the judgment below, it is affirmed, with costs. Affirmed.