United States. Patent Office · Washington, D.C., Govt. Print. Off. · leaf 663
formingan opening extending through the sound-modifier, .the two frusto-conical walls having acommon axis, and annular end walls arranged 100right-angularly to such axis and inclosing achamber between the frusto-conical walls,substantially as set forth. In testimony whereof I have affixed… … ^-r-Cg.ft. 3rrxxf.3.
Phonograph · Patents
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