harmonic bar extending above the whole length of the wrest-plank, which
it defends from any tendency to rise, by downward pressure obtained by
screws. During 1840-50, as many as five and even six tension bars were
used in grand pianofortes, to meet the ever increasing strain of
thicker stringing. The bars were strutted against a metal edging to the
wrest-plank, while the ends were prolonged forward until they abutted
against its solid mass on the key-board side of the tuning-pins. The
space required for fixing them cramped the scale, while the strings were
divided into separate batches between them. It was also difficult to
so adjust each bar that it should bear its proportionate share of the
tension; an obvious cause of inequality.

Toward the end of this period a new direction was taken by Mr. Henry
Fowler Broadwood, by the introduction of an iron-framed pianoforte, in
which the bars should be reduced in number, and with the bars the steel
arches, as they were still called, although they were no longer arches
but struts.

In a grand pianoforte, made in 1847, Mr. Broadwood succeeded in
producing an instrument of the largest size, practically depending upon
iron alone. Two tension bars sufficed, neither of them breaking into the
scale: the first, nearly straight, being almost parallel with the lowest
bass string; the second, presenting the new feature of a diagonal bar
crossed from the bass corner to the string-plate, with its thrust at an
angle to the strings.

There were reasons which induced Mr. Broadwood to somewhat modify and
improve this framing, but with the retention of its leading feature, the
diagonal bar, which was found to be of supreme importance in bearing the
tension where it is most concentrated. From 1852, his concert grands