The Germans are wont to annoy a garrison with the smoke of feathers,
sulphur and realgar, and they make this smoke last 7 or 8 hours.
Likewise the husks of wheat make a great and lasting smoke; and also
dry dung; but this must be mixed with olive husks, that is olives
pressed for oil and from which the oil has been extracted.
[Footnote: There is with this passage a sketch of a round tower
shrouded in smoke.]

The Danube.