Waltham 1899 model

This is an American Waltham 16 size movement, 15 jewels, 1899 model, grade 620. 

This is a good view of the "shipper" mechanism a lot of Walthams have for their "keyless works". When a pusher inside the winding arbor moves in and out, a clutch is activated changing to either turn the winding parts, or the setting parts.

Here are some images showing the serial number stamps on this 16 size Waltham pocketwatch; on the top plate, under the bottom plate, under the balance cock, and under the pallet bridge.