Patent lodged on 10th September 1806:
“Mr Laurent (Claude), who had long sought the means to remedy thetendency of flutes to alter their various tones due to the influence of hygrometric variations and wishing, at the same time, to render the sound of this instrument clean and with perfect purity, found crystal to be the right choice to give its sound the softness and purity he sought, in tones that remained the same and with an instrument that gave him the graceful note and faculty he longed for” (…) “These keys are embellished with jewels which shed lots of light over the instrument..”. The aesthetic charms of the instrument make it even more dreamlike to behold…
– http://www.crystalmusic.fr/en/orchestre/historical-instruments.html
