Specification of Joseph Francis Pratt : instruments for relieving deafness.

  • Pratt, Joseph Francis.
Date:
1861
Catalogue details

Licence: Public Domain Mark

Credit: Specification of Joseph Francis Pratt : instruments for relieving deafness. Source: Wellcome Collection.

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    o A.D. I860.—N° 2990. Provisional Specification. Pratt's Improvements in Instruments for Relieving Deafness^_ My Invention further consists in placing within hearing instruments resembling those previously described, a water cushion, metallic spring, or other vibrating substance for the purpose of modifying and softening the sound transmitted to the ears. LONDON: Printed by George Edward Eyre and William Spottiswoode,