|Photo courtesy of the Library of Congress|
Image courtesy of George B. Class at J. W. Pepper
Assuming the artistic rendering is reasonably accurate, it seems that the valve section on this horn matches the "upgraded" version seen in the photo at the bottom of the post below (which would then date that image to no later than 1899).
In particular, notice how the mouthpipe emerges from within a loop of tubing coming from the third valve, rather than following the main coil of the horn, and how there is a lack of excessive tubing to the right of the fourth valve - both of which are different from the image at the top of the post below.
What is even more interesting is this rare photo of Sousa's Band actually marching in a parade - something they are said to have done only eight times in their forty years of existence:
|Photo courtesy of Paul Bierley, The Incredible Band of John Philip Sousa, p. 24|
The event was to celebrate America's victory in the Spanish-American War, and in particular to honor Admiral George Dewey for what his naval forces accomplished. The date of the parade was September 30, 1899, and if you look closely all the way to the left, in the front row of the band, you'll see the Sousaphone.
Here is that horn enlarged from the photo. Details are not clear, but it appears to be that first "Monster."