The “Monster” was an early four-axle locomotive with all wheels driven. The original locomotive was built in 1834 by the Camden & Amboy. The cylinders were situated in an inclined position above the second axle and acted on a shaft at the front of the locomotive. This power was transmitted to the third axle via connecting rods and the coupling rods only drove the fourth axle. The third axle was driven by the second axle through a set of spur gears. Finally, a second set of coupling rods drove the first axle.

It was among the first, if not the first locomotive at all that was designed for burning anthracite. Its firebox had a combustion chamber and a water leg that created additional water circulation. In 1853, long after the original locomotive had been built, three more were built by the Trenton Locomotive Works. Some years later, Isaac Dripps rebuilt them to 4-6-0 locomotives. In this form, they were used until around 1875.