Mr. Nicol. Yes, sir; many times.

Mr. Eisenberg. Do you usually use photographs when you testify?

Mr. Nicol. No. As a matter of fact, I can't recall an instance in which I have.

Mr. Eisenberg. And why were these prepared?

Mr. Nicol. These were prepared at your request so that there would be documentary evidence of what I was observing. However—and this one, for example, will serve to illustrate the type of photography that is involved.

Mr. Eisenberg. Excuse me a second.

You are holding up a photograph labeled Q-1, K-1. Did you take that photograph, Mr. Nicol?

Mr. Nicol. Yes, this was taken under a comparison microscope.

Mr. Eisenberg. And Q-1 is one of the bullets which I have called the suspect bullets, and K-1 is the test bullet?

Mr. Nicol. Yes, Q-1 would be 399, and K-1 would be one of the projectiles in 572.