When it comes to the phrase "infernal machines," there are a range of other terms that can be used to describe these dangerous and potentially deadly pieces of equipment. Some possible synonyms include "explosive devices," "booby traps," "time bombs," "detonators," "incendiary devices," "bombshells," "firebombs," and "grenades." Each of these words captures a slightly different nuance of the term, but all evoke the sense of something that is designed to cause destruction or chaos. Regardless of the specific terminology used, it is important to treat any suspected infernal machines with the utmost caution and take appropriate measures to ensure public safety.