“Have you any copies of the forged certificates?” asked Craig.

“Yes, plenty of them.  Since the story has been told in print they have been pouring in.  Here are several.”

He pulled several finely engraved certificates from his pocket and Kennedy scrutinised them minutely.

“I may keep these to study at my leisure?” he asked.

“Certainly,” replied Carroll, “and if you want any more I can wire to Chicago for them.”

“No, these will be sufficient for the present, thank you,” said Craig.  “I shall keep in touch with you and let you know the moment anything develops.”

Our ride uptown to the laboratory was completed in silence which I did not interrupt, for I could see that Kennedy was thinking out a course of action.  The quick pace at which he crossed the campus to the Chemistry Building told me that he had decided on something.

In the laboratory Craig hastily wrote a note, opened a drawer of his desk, and selected one from a bunch of special envelopes which he seemed to be saving for some purpose.  He sealed it with some care, and gave it to me to post immediately.  It was addressed to Dawson at the Hotel Amsterdam.

On my return I found him deeply engrossed in the examination of the forged shares of stock.  Having talked with him more or less in the past about handwriting I did not have to be told that he was using a microscope to discover any erasures and that photography both direct and by transmitted light might show something.

“I can’t see anything wrong with these documents,” he remarked at length.  “They show no erasures or alterations.  On their face they look as good as the real article.  Even if they are tracings they are remarkably fine work.  It certainly is a fact, however, that they superimpose.  They might all have been made from the same pair of signatures of the president and treasurer.

“I need hardly to say to you, Walter, that the microscope in its various forms and with its various attachments is of great assistance to the document examiner.  Even a low magnification frequently reveals a drawing, hesitating method of production, or patched and reinforced strokes as well as erasures by chemicals or by abrasion.  The stereoscopic microscope, which is of value in studying abrasions and alterations since it gives depth, in this case tells me that there has been nothing of that sort practised.  My colour comparison microscope, which permits the comparison of the ink on two different documents or two places on one document at the same time, tells me something.  This instrument with new and accurately coloured glasses enables me to measure the tints of the ink of these signatures with the greatest accuracy and I can do what was hitherto impossible—­determine how long the writing has been on the paper.  I should say it was all very recent, approximately within the last two months or six weeks, and I believe that whenever the stock may have been issued it at least was all forged at the same time.