 Complete the following phrase:  In 1874 he was associated with David H. Dunham, of Dunham  Sons, with whom he patented improvements in iron frames and wrestplank bridges, and in 1877 the Mendelssohn Piano Company advertised their latest trichord squares used Mathusheks new Duplex Overstrung Scale, the greatest improvement in the history of Piano making, and claimed to have received uimous recommendation for the highest awards at the 