… is the evidence it provides about boats and inland waterways.
Here is an unreliable link to a painting called Grand Canal Harbour [click on the image to enlarge it] by Flora Mitchell. If the link doesn’t work, use this, which seems to be less flaky, and enter the two words canal and mitchell in the Quick Search box; you should get two thumbnails of canal paintings by Flora Mitchell.
[updated 20140922]
Irish waterways history 