John Trapp on Revelation 9:18

Verſe 18. The third part of men killed] Not only of Chriſtians, but alſo of their own:Turk hiſt. 1153 moſt of their poor being forced with victuals and other neceſſaries to follow their great armies in their long expeditions: of whom ſcarce one of ten do ever return home again, but there periſh by the way: if not by the enemies ſword, yet by the wants, intemperateneſſe of the air, or immoderate pains taking.

By the brimſtone] By the gun-powder, or by their ſulphured bowſtrings, which they diſcharge as out of their mouths, whereunto they draw or lay them.