[grundle]

The ‘ultimate evidence’ is the presence of different versions of the same letter, like capital “A” within text supposedly written all on the same typewriter back in 1961.

I saw that:

http://www.wnd.com/index.php?fa=PAGE.view&pageId=308397

[ponygirl]

I believe the BC is a composite of several different sources. Most of these letter differentiations can be explained by degradation of quality due to reproduction, faxing, digitizing, or even, as some have said here, fabric ribbon anomalies. What is striking to me looking at these letters side by side (haven't seen this table before; thanks for posting it) is that the second lowercase "a" is a different font. The stress on the counter of the "a" is almost vertical compared to the one next to it, which is more angled. Also, the bowl of the "a" (the little loop part) extends beyond the top serif much further than the "a" next to it does. It's a different x-height as well. Could be the result of stretching, or could just be a completely different font.

Look also at the serif on the descender of the "y". See how the second one almost curls back on itself? The first one does not. Different font. These are tiny little details that type designers put into their faces that most people would never notice. Degradation doesn't explain the serif on that "y."

Sometimes fonts are redrawn and re-released; even though they have the same names (say, "Helvetica" or "Courier") a trained eye can tell they are different and one was created in say, 1920 and the other one redrawn digitally in 2005.