Here's the actual letter in which Sam Arnold instructs Al Emmett Fostell to write to photographer J. Orville Johnson and request a copy of his Charles M Prout photo. This letter is not in the collection of the Abraham Lincoln Library and Museum in Harrogate, Tennessee, but was in an auction in 2012:
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EDIT: I just want to add that this trivia question was great fun to me. Particularly because part of the stats I can see for my blog is when people visit my website based on google searches. I had two people visit my site today using the searches of ""al emmett fostell" "o'laughlen"" and "photo under false name "spangler" ford's". You guys certainly do your research for these trivia questions!