Bowl shape and heel marks.
Pipe bowl form changes decade by decade from c.1580, making clay pipes excellent dating tools. The direction of travel is from tiny bowls (tobacco dear) to large ones (tobacco cheap), with the bowl’s angle and lip also shifting by fashion.
Maker marks appear on the heel or spur — initials, symbols, sometimes full names — and can often be traced to a documented pipemaker in the town’s records.
Bore diameter of the stem narrows over time — a rough statistical aid on plain stem fragments, useful in quantity, never on one stem alone.
Decorated bowls (ships, arms, sporting scenes) are largely nineteenth-century. Record bowl form against a published series, the mark, and the bore; a complete marked bowl can date a deposit to within twenty years.
Identifying agricultural tools