That leaves me solely to rely on an All Points Bulletin to researchers knowledgeable about uniforms—military and others—who might somehow render an answer, or at least provide further guidance.
Until then, the only thing I can surmise from the photograph is that the subject, somehow, may be a relative of William or Sarah Swanton Tully. Because the picture was taken at Jarmuth, a studio at 9120 Commercial Street in Chicago, the field of possible suspects may further be limited. Jarmuth, in fact, was the studio mentioned by William’s daughter Edna in her diary, where she had her picture taken for her “sweet 16” birthday. Perhaps others in the family had patronized the studio previously, and young Edna was merely following suit.
Yet, the facial features of both John Tully (Edna’s uncle, the policeman) and cousin William Tully (John’s son and Edna’s cousin, seen at far left in his sister’s wedding photo, who may have donned a uniform for his work as a street car conductor) don’t resemble the subject of this portrait. Edna’s father, himself, had served for a while as a railroad engineer, but it is doubtful that this type of garb would be used in that venture; at any rate, his 1896 death certificate noted his occupation at that time to be merchant, for which no uniform would generally be required.
I will have to be satisfied, at this point, in setting aside the portrait of this dignified gentleman until someone with further knowledge of clothing styles of that era can shed some light on possible parameters for his identity.