Volney Mathison, an early Dianeticist who, after listening to a lecture by LRH outlining the equipment and circuits necessary to detect mental charge, built the first E-Meter in 1951, the Model B. There were various other models of E-Meters built by Mathison which were used by auditors. The E-Series in 1954 was his lastmodel a s his meters had become too complex to be workable. —PDC Volume 1 Approved Glossary