One of the most obvious problems with John Richter's identification of Lincoln in the two Gardner photos is that the beard simply does not match the style of beard that Lincoln was wearing in November 1863. As is apparent from studying the several portraits of Lincoln recorded in Washington just eleven days before the ceremonies at Gettysburg, Lincoln's beard was essentially disconnected at that time (as it frequently was), with an unmistakable gap between his goatee and his sideburns -- completely unlike the solid mass of facial growth visible on the man identified by John as Lincoln. (See also the detail of Lincoln on the speakers' stand at Gettysburg; the most revealing version is reproduced in James Mellon, The Face of Lincoln, pg. 141.)
Equally troublesome is the fact that John's scenario has the two photos depicting Lincoln leading the civil portion of the procession into the National Cemetery, heading from left to right toward the speakers' stand. This scenario seems incongruous to me because the same images likewise depict the speakers' stand already packed with people. Since the vast majority of the occupants of the speakers' stand would have been the same government officials, dignitaries, and sundry participants who followed Lincoln into the National Cemetery via the procession, it doesn't make any sense that the speakers' stand would already be packed just moments before the arrival of most of its intended occupants.
Furthermore, the mounted individual identified by John as Lincoln is clearly facing northwestward, and in a direction away from the already crowded speakers' stand -- with this same individual remaining in a static position throughout the recording of both negatives, indicating that he was not heading anywhere in particular at the time the two negatives were recorded.
Moreover, Lincoln did not ride alone in the procession to the National Cemetery. Indeed, it is well documented that Lincoln was accompanied and flanked by several mounted civilians, including the chief marshal and three members of Lincoln's cabinet (one of whom was six-feet-tall and undoubtedly wearing a hat). The individual identified by John as Lincoln appears to be completely unaccompanied by any mounted escorts.
According to the official program, the military contingent, which immediately preceded the civil portion of the procession into the National Cemetery, was supposed to move into a line formation and salute the President as he passed by en route to the nearby speakers' stand. If there were any members of the military contingent whom one would expect to be part of this solemn "salute", it would be the soldiers who so dominate the foreground of both Gardner photos. Instead, we see these soldiers relaxing in an "at rest" posture, with at least one of them seated on the ground and casually facing the camera. Could it be that literally moments before the two photos were recorded, these same soldiers were standing at attention and saluting their Commander in Chief? According to John's scenario, the President is still passing by as these soldiers are seen lounging in the foreground.
My next problem with John's Lincoln identification deals with the format in which both images were recorded, i.e., stereo. It is inconceivable to me that a photographer as experienced as Gardner would have considered it even remotely possible to actually document a specific individual from that distance, and especially while employing his stereo camera. Had Gardner truly been obsessed with recording multiple plates of Lincoln (as John's subjective scenario suggests), he almost certainly would have selected his larger 8X10-plate camera rather than his stereo camera. The substantially longer focal-length lens used with the former camera was literally telescopic in nature when compared to the decidedly more wide-angled twin lenses used with the latter. And the finished print would have been more than four times larger, thereby increasing dramatically the chance that an obscure individual in the distant background might be recognizable (albeit only under magnification).
Not surprisingly, the individual identified by John as Lincoln appears as little more than an off-centered and completely unrecognizable black speck in the distant background of contact prints made from the original stereo negatives. It is my opinion that Gardner was simply taking two successive negatives while in the process of recording general overviews of the ceremonies that day; and that the off-centered, little black speck identified by John as Lincoln (using technology never envisioned by Gardner) was hardly the focus of Gardner's attention.
Given all of the above, it seems evident to me that the two Gardner stereos were recorded subsequent to the occupation of the speakers' stand by both Lincoln and the numerous dignitaries who followed him into the National Cemetery; that the military had already dispersed to accommodate the lengthy arrival of the remainder of the civil groups in the procession (with a cavalry contingent facing northeastward to maintain a corridor for the latter -- and with the soldiers in the foreground having already formed a cordon along the edge of the crowd); and that the lone, generically top-hatted and bearded man identified by John as Lincoln, was almost certainly not Lincoln -- who, by that time, would already have been seated on the speakers' stand, patiently waiting for the next phase of the ceremonies to begin, i.e. the speeches, etc.
If not Lincoln, who then was this unidentified bearded man seen wearing a top hat in the two stereo views? He was undoubtedly nothing more than an anonymous, historically insignificant civilian official, most likely associated with one of the numerous civil organizations that followed the dignitaries into the National Cemetery that historic day.