It's sad that the Old South Church is forced to sell it (although it helps that they have two copies) but it's good news for raising awareness of printing.

What was the font?

hhp

Um,

http://en.wikipedia.org/wiki/File:Bay1640.jpg

I'd say Caslon. Which is not surprising. But in fact, it would be surprising, since even if the book was printed in 1640 instead of 1610, that's still over 50 years before Caslon was born.

As it happens, though, that title page was reproduced in Updike's Printing Types, so identifying the typeface shouldn't be a problem.

Hmm... further searching turns up

http://typefoundry.blogspot.ca/2011/11/elzevir-letter.html

showing that the "generic" typeface of the 17th Century does have a somewhat mysterious origin - even though it was the Elseviers that everyone was copying.

So maybe it's a Dutch font (since that's where the Brits used to get theirs). I will check my Updike though.

hhp