United States. Patent Office · Washington, D.C., Govt. Print. Off. · leaf 987
38^ Tf#.6. 33- F2 > *a t$®£ YZ73/ / n ^ INVENTOR. COLUMBIA PLANOORAPH CO., WASHINGTON, D. C. 1,159,023. C. M. HECK.METHOD OF COMPARING SOUNDS. APPLICATION FILED JULY 7, 1915. … Patented Nov. 2,1915. 2.SHEETS-SHEET 2.
Phonograph · Patents
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