I found my way to the Library of Congress from Chicago after a few adventures on the road, but I'm going to leave those stories for another post.
The Rare Books & Manuscripts division is in the Jefferson Bldg. They have a few nice books there & I got to see more than just two.
However, it was a treat to look at two different copies of the 1545 Libro nuovo d’imparare a scrivere that they hold. One is the Rosenwald copy and the other is the Fabyan copy.
The 1545 copy is a reprint from the 1540 publication. I haven't looked at two copies of the same title of any writing manual from the same issue date. At Iowa I'd taken a look at 3 Bickhams from different years and the production variations were evident. I thought it might be fun to see what kind of variations there would be in two books from the same publication date and presumed that they were from different printings of the same year.
The Rosenwald copy isn't trimmed as tight as the Fabyan. There are more generous margins on the Rosenwald book.
The paper looked the same as I started to go through it and the printing was comparable in terms of coverage. Inking on the reverse blocks varies but that's to be expected.
I kept looking for a variation in block formatting or change in something as I went through the books.
The imposition of blocks was the same throughout the books. As I was going through them, I noticed a variation in the signature marks at Cii - not surprising if they were printed at different times.
When I went through the books a second time, I got a little excited because I hadn't seen any other variation i the printing order or blocks. The rest of the letterpress was all the same.
Then I went through them again and looked at how the blocks lined up and looked for obvious variations in the show-through and found so much similarity in impression and inking and paper that I suspect they were printed in the same press run.
The Fabyan copy has an owner's practice on the verso of the last page.
I mentioned this possibility to Mark Dimunation and he seemed interested. When I return, I'll gather more information and see if my theory holds up to greater scrutiny.