So far, I have scanned them, retouched them, compressed them, tested them in a range of converted file types, and generally mucked about with them, and then created lower resolution ones for display and review on the website.
By their very nature wood engravings are often quite small, and although look lovely as a print, on screen you often need to see them at a slightly larger scale if you really want to scrutinise them. This leads open the opportunity for anyone to drag a copy off their browser and use it at screen size (are you following?) ie, 'pirate' it.
I have been advised by those that know to show all engravings with a watermark, so I have been experimenting (and bear in mind I need to do this to lots and lots) with watermarks.
The image above is actually a tiny engraving - about an inch square (25x25mm for those that think in metric) - with watermark in place. I guess it's a fine balancing act - not too intrusive, but gets the job done.