Starting around the middle of the century, the authenticist approach was given new impetus by the work of the builders Frank Hubbard and William Dowd, working in Boston, and Martin Skowroneck, working in Bremen, Germany. These builders based their construction on painstaking research: they took apart and inspected many old instruments and consulted the available written material on harpsichords from the historical period. These mid-century authenticist instruments proved very popular, and many other builders soon followed the example of Hubbard and his colleagues.