Fujitsu ScanSnap N1800 Operator's Manual page 237

HINT
The stacker holds the document sheets after they have been scanned. It can be pulled
out and adjusted to the size of the document being scanned.
4. Load the documents into the ADF paper chute.
Load the document front side down, with the top of the document entering the
scanner first (when multiple document sheets are loaded, the last page is on the
top).
HINT
If [Face-up] is selected on the [Paper Face Direction] window, load the document front
side up, with the bottom of the document entering the scanner first.
For details about how to load the document, refer to
(page 309).
"6.9.6 Document Feed Direction"
237
6.1 Loading Documents