Two post-office clerks had been used as witnesses at the trial, of whom the elder, Mr. Curlydown, had been by no means a constant or an energetic witness.  A witness, when he is brought up for the defence, should not be too scrupulous, or he will be worse than useless.  In a matter of fact a man can only say what he saw, or tell what he heard, or declare what he knew.  He should at least do no more.  Though it be to save his father, he should not commit perjury.  But when it comes to opinion, if a man allows himself to waver, he will be taken as thinking the very opposite of what he does think.  Such had been the case with Mr. Curlydown.  He had intended to be very correct.  He had believed that the impression of the Sydney stamp was on the whole adverse to the idea that it had been obtained in the proper way; and yet he had, when cross-examined, acknowledged that it might very probably have been obtained in the proper way.  It certainly had not been ‘smudged’ at all, and such impressions generally did become ‘smudged.’  But then he was made to say also that impressions very often did not become smudged.  And as to the word ‘Nobble’ which should have been stamped upon the envelope, he thought that in such a case its absence was very suspicious; but still he was brought to acknowledge that post-masters in provincial offices far away from inspection, frequently omit that part of their duty.  All this had tended to rob the envelope of those attributes of deceit and conspiracy which Sir John Joram attributed to it, and had justified the judge in his opinion that Mr. Curlydown’s evidence had told them little or nothing.  But even Mr. Curlydown had found more favour with the judge than Samuel Bagwax, the junior of the two post-office witnesses.  Samuel Bagwax had perhaps been a little too energetic.  He had made the case his own, and was quite sure that the envelope had been tampered with.  I think that the counsel for the Crown pressed his witness unfairly when he asked Mr. Bagwax whether he was absolutely certain that an envelope with such an impression could not have passed through the post-office in the ordinary course of business.  ‘Nothing is impossible,’ Mr. Bagwax had replied.  ’Is it not very much within the sphere of possibility?’ the learned gentleman had asked.  The phrase was misleading, and Mr. Bagwax was induced to say that it might be so.  But still his assurance would probably have had weight with the jury but for the overstrained honesty of his companion.  The judge had admonished the jury that in reference to such a point they should use their own common-sense rather than the opinion of such a man as Mr. Bagwax.  A man of ordinary common-sense would know how the mark made by a die on a letter would be affected by the sort of manipulation to which the letter bearing it would be subjected;—­and so on.  From all which it came to pass that the judge was understood to have declared that that special envelope might very well have passed in ordinary course through the Sydney post-office.