Determining the date of historical photos

All the shadows in the picture-those of Mr. Top-Hat-and-Tails, his dead horse, the buildings, and the man with his dog-stretch directly across the street. Since S. 8th St. (then Griffith St.) runs north-south, the shadows point almost exactly east-west. There are only two days in the year when this occurs, the Spring Equinox (March 19-20) and the Fall Equinox (September 22-23). On these two occasions, the night and day are of equal length everywhere on earth, as the sun rises due east and sets due west. On other dates, the sun rises either north or south of east and sets either north or south of west, as the days become longer or shorter and the seasons change. Considering a top hat and tails are not the appropriate attire for Sheboygan in March when the average temperature is about 32°F, the date the picture must have been September 22-23.

I don’t know how I found this document a few years ago, but the previous post jogged my memory. Historical analysis of photography fascinates me. Errol Morris’ recent investigative blogging about photography for the New York Times is a prime example. In A Dead Horse of a Different Color by Colleen Fitzpatrick and Andrew Yeiser (PDF), we get a similar walkthrough of the process of determining the facts behind a photograph, in this case, the exact time and date of a photo from 1871. By analyzing shadows and investigating the history of photographic lenses and cameras and researching the history of railroads in Wisconsin, the researchers determined that the photo was likely taken September 24, 1871 at 4:30 pm by either Wolfgang Morganeier or his two apprentices, George and Edward Groh.

And if you’re into this sort of thing, there are weekly photo quizzes at Forensic Genealogy.

(I linked to this in the previous post, but felt it should be a post of its own…)