The tamper was a flat steel plate on a handle. You lifted it and dropped it. Lifted it and dropped it. The plate hit the ground and the ground compressed. The gravel settled. The dirt packed. The sand leveled. The tamper was gravity applied on a schedule. Lift. Drop. Lift. Drop. The rhythm was the technique. The speed did not matter. The consistency mattered. A hundred even drops packed the ground better than fifty hard drops because the even drops gave the ground time to settle between impacts.

The hand tamper was a square plate welded to a steel pipe. The pipe was the handle. You held the pipe with both hands and lifted the plate to waist height and let it fall. The fall was three feet. The weight was twenty pounds. Twenty pounds falling three feet produced enough force to compress loose gravel into a solid base. The base held the concrete. The concrete held the building. The building started with a man lifting a plate and dropping it until the ground stopped moving.

The vibrating plate tamper replaced the hand tamper on big jobs. A gasoline engine spinning an eccentric weight on a steel plate. The plate vibrated and the vibration shook the particles into alignment. The particles nested against each other like eggs in a carton. The nesting was the compaction. The vibrating tamper compacted in minutes what the hand tamper took hours to achieve. The vibrating tamper was louder. The hand tamper was quieter. The hand tamper let you hear the ground changing. The sound of the drop changed as the ground got harder. A soft drop meant more work. A hard ring meant done. The vibrating tamper drowned out the feedback.

You tamped in layers. Four inches at a time. You could not dump twelve inches of gravel and tamp the top and expect the bottom to compact. The bottom would stay loose. The top would be hard. The base would fail from underneath. The builder who tamped in layers built a base that held. The builder who tamped in one pass built a base that settled. The settling cracked the concrete and the cracked concrete cracked the building. The failure started twelve inches underground in a layer that nobody tamped.

Nobody hand-tamps anymore except in tight spaces. The space between the foundation wall and the property line. The space around a pipe. The space inside a post hole. The tight space is where the machine cannot fit and the hand tamper comes back. The hand tamper is the tool of last resort. The machine does the field. The hand does the corners. The corners are where the failures start because the corners are where the machine cannot reach and the hand gets lazy. The builder who hand-tamps the corners with the same care as the machine tamps the field builds a foundation that does not crack at the edges.

See also: Footing, Sleeper