The Magnetic Acceleration Cannon was built into the tripods' weaponry systems. It launched black smoke into the air as an attempt to exterminate the Human population. According to the Martian Technology Report: The Martians made surprisingly little use of any analogue to terrestrial artillery. For the most part they relied upon their Heat-Rays to quash any resistance to their conquest. The only occasion on which they used any sort of ballistic weapon was in the delivery of their dreadful canisters of Black Smoke. This powder was dispensed by means of canisters fired from reusable tubes, wielded by the Martian Fighting Machines."