General characteristics and operational history of the Plunger-Class submarines in 20th century naval development
The A class submarine was developed in 1911 from the Plunger-class submarines, which played a significant role in the early development of the U.S. Navy's quiet service. Their pre-war midget design, which was based in the Philippines, had an Electro Dynamic electric motor, an Otto petrol engine, and a 60-cell battery.