Chapter II: TECHNOLOGY.--A Quick Way to Ascertain the Focus

of a Lens.--1 diagram.

The History of the Pianoforte. By A.J.
HIPKINS.--Different parts of a pianoforte and
their uses.--Inventor of the instrument and his
"action."--First German piano-maker.--Square
pianos.--Pianos of Broadwood, Backers, Stodart,
and Erard.--Introduction of metal tubes, plates,
bars, and frames.--Improvements of Meyer, the
Steinways, Chickerings, and others.--Upright
pianos.--Several figures.