This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Ahrons Steam Locomotive Construction and Maintenance Fig. Markingoff cylinder port faces Original Steam Locomotive Construction and Maintenance Fig Scan Internet Archive archive org Ahrons PDoldauto PDold Scans from Ahrons Steam Locomotive Construction and Maintenance Steam engines with slide valves