1 As when that devilish iron engine, wrought 2 In deepest hell, and framed by Furies' skill,

framed > fashioned

3 With windy nitre and quick sulphur fraught,

windy > {Generating wind, gas} nitre > {Saltpetre or potassium nitrate, a component of gunpowder} quick > readily inflammable fraught > filled

4 And rammed with bullet round, ordained to kill,

bullet > cannon-ball

5 Conceives fire, the heavens it does fill

Conceives fire > Detonates

6 With thundering noise, and all the air does choke, 7 That none can breathe, nor see, nor hear at will,

That > [So that]