In 2007 on this thread,
https://www.ancestry.co.uk/boards/thread.aspx?mv=flat&m=430&p=surnames.sladethe person who started the thread said, farther down the page, that she had some photos of the family.
[edited and deleted some specifics here]
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Some county histories have biographies with photographs of the men included. I found a few for Franklin County, but none with photos. Here is a link to the one with the most information about Joseph W Slade, in case you haven't found it yet.
http://iagenweb.org/franklin/1883Biographies/1883S_Bios.htm----
I didn't find a passport application for him. The 20th century ones, at least, sometimes have photos.
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He and the family are in an awful lot of trees on ancestry, but no photo of him. One of his daughter Mary Ethel has made the rounds, but not her father.
Edit to add:
Oops.
that's you! as an afterthought I said to myself 'maybe she is on rootschat.'
[reedited and deleted the link to a rootschat thread and some specifics here. They were unrelated to the Slade surname]
Oh well, I'll leave the [rest of the] information for the next person. I hope you find a photo. I have a few of my great-grandparents and of some of their siblings, and one from the generation before that, so it is stretching it a bit, but there might be one out there.