I think you're right. Great photo - I have a much smaller version in my files but it was attributed to Bliss - wrongly, it seems. My version is so small you can't even make out the face of the Indian. The stripes on the tipi reminded me I'd seen it somewhere before.
Here's another that may be Bliss or Soule or...
Last Edit: Jul 19, 2019 13:16:04 GMT -5 by grahamew
The identifications above are hard to read. I tried to improve on the IDs below. Note that Cowan´s Auctions stated one officer in the picture is Owen Hale of the 7th Cavalry. He is rather Lt. Joseph Hale of the U.S. 3rd infantry.
There are still some open questions, for example:
Who are the English travellers?
Can we identify the Arapahoe men?
Last Edit: Jun 26, 2017 17:08:05 GMT -5 by Dietmar