Per Unique at Penn's Mitch Fraas (excerpts):
All of the illustrations here come from early explosives and warfare manuals copied and re-copied with alterations between the 16th and 17th centuries. The immediate originator of the idea behind these cat and bird bombs was Franz Helm of Cologne, an artillery master in the service of various German princes who likely served in campaigns against Turkish forces during the mid-16th century. He wrote a treatise on siege warfare (Buch von den probierten Künsten) and artillery that circulated widely in manuscript, but was not published in print until 1625.
In the text accompanying the images is a section entitled “To set fire to a castle or city which you can’t get at otherwise” . This section details how to use doves and cats loaded with flammable devices to set fire to enemy positions. On cats the text paints a grisly picture of attaching lit sacks of incendiaries onto the animals to have them return to their homes and set fire to them. In my awkward translation:
“Create a small sack like a fire-arrow … if you would like to get at a town or castle, seek to obtain a cat from that place. And bind the sack to the back of the cat, ignite it, let it glow well and thereafter let the cat go, so it runs to the nearest castle or town, and out of fear it thinks to hide itself where it ends up in barn hay or straw it will be ignited.”
From BibliOdyssey, some general (animal-free) illustrations of explosives: