Fun group of cards showing a variety of things.
I agree, Merkle is definitely a wet sheet transfer.
Easterly and O'Hara are printer's alignment marks to help register the image.
Sullivan is a bit of a top-bottom miscut. The line parallel to the top border is a crop mark to show the printer where to cut the sheet. The other line that slashes down the card is a scratch in the plate - there is a thread keeping track of these cards, also pointed out by Zach (
http://www.net54baseball.com/showthr...late+scratches). If Sullivan isn't on there you should add it.