Ferrara's Astounding Subterranean Drilling Momentum Facilitator

Obsessed with tales of the ratmen who supposedly dwelt beneath the surface of the Old World, Avel Ferrara decided to find out for himself whether or not such a race of creatures existed. Assisted by his sons, he developed a larger form of drill bit and began attempting to explore the world beneath the streets using his Facilitator. Ferrara never found any evidence of these ratmen, but the military applications of his device were quickly realised when who swathes of city streets subsequently collapsed along his route of travel. Several of Ferrara's devices were constructed to take part in the sieges of a number of castles in the Border Princes. These proved extremely successful, bringing down the walls of three castles within a week of the siege beginning. Unfortunately all three devices were lost and Ferrara had, by this time, moved onto other devices to help him realise his dream of proving that the foul ratmen actually do exist.

Source
pg. 55
 * White Dwarf #296