William Brockendon’s invention for drawing wire through holes in diamonds and rubies, in 1819,⁵⁰² established an efficient process for the production of hard drawn steel wire. Alpheus Babcock’s one piece iron frame patented in 1825, and Henri Pape’s expansion of the keyboard compass to 97 notes in 1842, were pivotal piano design responses to steel wire tensile strength improvements. It is widely acclaimed that it was the desirable tonal improvements of the higher tensioned drawn steel wire which directed the major change from wooden to iron framed pianos, and the subsequent developments of steel tensile strength and wire hardness by Moritz Poehlmann of Nuremberg in the 1850s, that brought about a standardised piano tone.

…all the leading piano manufacturers of Europe and America adopted the Poehlmann make for their pianos. ⁵⁰³

Between 1867 and 1893, music wire tensile strength increased by 44%.⁵⁰⁴

1a.3 String Scaling C2, C3, C4, C5

String speaking lengths- are measured from the bridge agraffes or pins to the tuning bar or capo bar agraffes.

All these strings on the Steinway piano are terminated by an agraffe on the tuning pin plate and a dense felt stringing pillow at one end with two bridge pins at the other. In the Stuart piano one of two agraffes is housed in a capo bar with a counter agraffe on the tuning pin plate with a dense felt stringing pillow behind that. At the other end is a bridge agraffe. The deflection of the string pathway is fundamentally different and thus, the attack and decay transients.⁵⁰⁵

Wire Tensile strength is measured by the nominal breaking load, newtons / length2 (N/mm²)

Thickness is measured by mm of the cor diameter of the pure music wire for the treble strings, and cover + cor diameters of the wound bass strings. (C2)

In harmonicity:
In harmonicity produced from wire stiffness and string length variations is
only a minor part of the practical application of the stretched string.
 String terminals are more influential on what is actually heard and the
 acceptance of the in harmonicity levels. Stephen Paulello and I have
 discussed this matter and agree on this point. In effect, the way in harmonicity garb is tossed around by techo’s is mostly rubbish and
 meaningless in practical piano making as other factors have greater
 influence on the sound. The bridge agraffe reduces the heard in harmonicity factor significantly as the string is held more accurately.⁵⁰⁶

Yield is the percentage of elasticity the string can be stressed to, to achieve maximum tonal spectra.

Simply, the closer the music wire is taken toward the yield point the more efficient it becomes. The consequence of this increased efficiency is more sustain/resonance, power and tuning stability producing a better all round sound quality.⁵⁰⁷

^{502     5}Wolfenden, 6.
^{503     2} Dolge, 124
^{504     6}Wolfenden,7
⁵⁰⁵ Wayne Stuart email interview Wayne Stuart with author,24thMarch, 2014.
⁵⁰⁶ Wayne Stuart email interview with author, 20th March, 2014.
⁵⁰⁷ Wayne Stuart email interview with author, 24th November , 2012.