Patent 831188 does indeed describe the particular device (a Phonograph Tone Regulator to use the inventor's words) shown in the eBay reference. There are two additional references in the third paragraph of the patent that read:
"My invention is in some respects an improvement upon the device of my prior patent No. 778,271, for phonograph issued to me December 27,1904, and as to its principal features is a division of my Application for patent on phonograph, Serial No. 251,470, filed March 22, 1905." The Application for patent on phonograph, Serial No. 251,470, filed March 22, 1905 was issued as patent 813670 on Feb 27, 1906. Patent 83118 was applied for on Dec 30, 1905 and issued on September 18, 1906. The Dec 27, 04 stamp is a reference to the principal invention (778271) described in the early (earliest) patent and not the physical implementation of it described in the later one (831188). All three patents (links below) are the work of Eugene M. Robinson. Here are the three links: Patent 778271: http://www.google.com/patents?id=1I1TAAAAEBAJ&dq=778271 Patent 831188: http://www.google.com/patents?id=DiluAAAAEBAJ&dq=831188 Patent 813670: http://www.google.com/patents?id=I1BEAAAAEBAJ&dq=813670 Walt
