Watch this 1937 short film, "Spot News," which should shed some light on exactly what a "wire photo" is and the process by which they were produced:
http://www.youtube.com/watch?v=LRTlm_cKZ8Y
The photo you see them attaching to the cylindar on the sending end is the Type 1, Original, 1st Generation print made from the original negative. It would have a paper caption
affixed to the
front of the photo so that, when the photo was developed on the receiving end, that same caption text would be embedded in the image, actually part of the photo produced on the receiving end. The photo produced on the receiving end would be the Type 3, Second Generation, Duplicate, Wire Photo. Either the Type 1 or the Type 3 may have additional editorial comments, markings or stamps on the back, though it is very common for a Wire Photo to have no markings or only a stamped file date on the back since most of the necessary information is contained in the embedded caption text on the front. Also, both Type 1 and Type 3 photos may have crop marks, touch-up/masking paint, or other editorial markings on the front, depending on their use and the whims of the editor.
Also keep in mind that MANY sellers, collectors, and auction houses will mistakenly refer to ALL news/press photos as "wire photos" (which is especially humorous for those early photographs produced before the wire photo process was invented).
P.S. The Bobby Richardson photo that I posted earlier is a Type 3 "Wire Photo." Technically a second generation image, since it was produced by duplicating a print via the wire photo process rather than developed from the original negative.
P.P.S. The sellers like Henry Yee, who deal primarily in vintage sports photography AND who are knowledgable about both the photographs themselves
and the subjects they depict, are few and far between. There are several who are members here though. There are also a number of sellers on eBay who are, shall I say,
efficient at selling large numbers of news photos on eBay, yet apparently know little or nothing about what they are selling. Players' names are misspelled, obviously incorrect dates for depicted events are given, terms are misused, etc. Thankfully, most of these sellers also post large and clear enough scans of the front and back that, if YOU know what to look for, you can disregard most of what they have written and decide for yourself whether to go after the photo or not (and as others have pointed out, may wind up getting a bargain
because of the seller's mistakes).