The date on the envelope,—­the date conveyed by the impression, to which so much attention had been given,—­was 10th May 1873.  Bagwax had succeeded in getting covers bearing dates very close to that.  The 7th of May had been among his treasures for some time, and now he had acquired an entire letter, envelope and all, which bore the Sydney impression of the 13th May.  This was a great triumph.  ’I have brought it within a week,’ he said to Curlydown, bending down over his glass, and inspecting at the same time the two dates.

‘What’s the good of that?’ asked Curlydown, as he passed rapidly under his own glass the stamps which it was his duty to inspect from day to day.

‘All the good in the world,’ said Bagwax, brandishing his own magnifier with energy.  ‘It is almost conclusive.’  Now the argument with Bagwax was this,—­that if he found in the Sydney postmarks of 7th May, and in those of 13th May, the same deviations or bruises in the die, those deviations must have existed also on the days between these two dates;—­and as the impression before him was quite perfect, without any deviation, did it not follow that it must have been obtained in some manner outside the ordinary course of business?

‘There are a dozen stamps in use at the Sydney office,’ said Curlydown.

’Perhaps so; or, at any rate, three or four.  But I can trace as well as possible the times at which new stamps were supplied.  Look here.’  Then he threw himself over the multitude of envelopes, all of which had been carefully arranged as to dates, and began to point out the periods.  ’Here, you see, in 1873, there is nothing that quite tallies with the Caldigate letter.  I have measured them to the twentieth part of an inch, and I am sure that early in May ’73 there was not a stamp in use in the Sydney office which could have made that impression.  I have eighteen Mays ’73, and not one of them could have been made by the stamp that did this.’  As he spoke thus, he rapped his finger down on the copy of the sacred envelope which he was using.  ‘Is not that conclusive?’

‘If it was not conclusive to keep a man from going to prison,’ said Curlydown, remembering the failure of his own examination, ’it will not be conclusive to get him out again.’

’There I differ.  No doubt further evidence is necessary and therefore I must go to Sydney.’

’If it is conclusive, I don’t see why you should go to Sydney at all.  If your proof is so perfect, why should that fellow be kept in prison while you are running about the world?’

This idea had also occurred to Bagwax, and he had thought whether it would be possible for him to be magnanimous enough to perfect his proof in England, so as to get a pardon from the Secretary of State at once, to his own manifest injury.  ‘What would satisfy you and me,’ said Bagwax, ‘wouldn’t satisfy the ignorant.’  To the conductor of an omnibus on the Surrey side of the river, the