Which type of incendiary device is NOT mechanical?

The correct answer is chemical devices, as they do not rely on mechanical components or mechanisms to ignite or propagate a fire. Instead, chemical incendiary devices work through the reaction of specific substances or compounds that produce heat or flames when combined or exposed to certain conditions.

Mechanical devices, on the other hand, utilize physical components to create a fire. For example, pneumatic devices employ air pressure to trigger ignition, while electrical and battery-operated devices utilize electrical currents and energy storage to operate. Each of these types involves a mechanical aspect, allowing them to ignite an incendiary reaction through various mechanical processes. Hence, chemical devices stand apart from this category as they depend solely on chemical reactions rather than mechanical actions to function.