McKIM v. THOMPSON.—1 BLAND. 151

purchase money was really due or not. And being necessarily in-
volved in the main question, the Court will not stop or delay the
regular progress of the case to investigate or establish it by affi-
davits or proofs taken out of the regular order. The proof of pos-
session, and the acts of ownership, lay the foundation of that
equity which entitles the vendor to make the call for his money
sooner than he otherwise could do; and, in that class of cases, it
is said to be now quite decided, that, upon motions of this sort,
affidavits of such collateral circumstances may be read, and that it
was a practice to be encouraged, as it shortened pleading. Clarice
v. Wilson, 15 Ves. 317; Cutler v. Simons, 2 Meriv. 103; Morgan v.
Shaw, 2 Meriv. 138; Crutchley v. Jerningham, 2 Meriv. 502; Bram-
ley v. Teal, 3 Mad. 219; Wickham v. Evered, 4 Mad. 53; Blackburn
v. Starr, 6 Mad. 69; Wynne v. Griffith, 1 Sim. & Stu. 147; Gill v.
Watson, 2 Sim. & Stu. 402.

But there is an obvious distinction between such collateral cir-
cumstances and peculiar equity, and the admission or establishment
of facts, which go to shew the real title to the fund proposed
* to be called in. Therefore, the proofs and exhibits that
have been taken and brought in under the order of the 10th of May
last, must, upon the present occasion, be laid aside as altogether
inadmissible.

Having thus disposed of the proffered auxiliaries of the plain-
tiffs, let us now take a review of those tendered by the defendant
Thompson. He insists, that a certain paper he has presented as a
supplemental answer, ought to be considered as an amended answer,
or that he ought now to be permitted to file a supplemental answer
as prajed by his petition.

It is with great difficulty permitted to a defendant to make any
alteration in his answer, even upon a mistake. And there is no
instance of its having been allowed for the purpose of retracting
a clear and well understood admission. Pearce v. Grove, 3 AtJc.
522, It should appear due to general justice to permit the issue to
be altered. The rule upon this subject is, that the defendant must
move to put in a supplemental answer, and accompany the motion
with an affidavit, in which he must swear, that when he put in the
answer, he did not know the circumstances upon which he applies,
or any other circumstances upon which he ought to have stated the
fact otherwise, or that when he swore to his original answer, he
meant to swear in the sense in which he now desires to be at liberty
to swear. Livesey v. Wilson, 1 Ves. & Bea. 149.

The paper tendered as an amended answer, comes within no
part of this rule. It is silent as to the causes which occasioned
him to omit mentioning the new matter, therein contained, in his
original answer; nor does it say anything of his not knowing of
the new circumstances therein disclosed. It, in fact, purports to
be a mere additional or amended answer, proposed to be put on