Thanks to the generosity of Nick, here is a photo of "Snowball."
Nick writes, "The photo is signed to "Mr Blake" - this is Jack Blake, a British trumpet player from the very early days of dance music in London (he was at Rectors Club and the Hammersmith Palais de Danse and knew the ODJB and Bechet). At the time the photo was given to him, Blake was in partnership with Ellis Jackson, a black American trombonist, dancer and singer (who joined Billy Cotton's band in 1931). From the late 1920s until 1931, they had a music hall act called "Blake and Jackson" that interspersed singing and playing with comedy patter, and they even made a Phonofilm short movie, which I have seen (it's very corny but good fun!). Blake's real name was Jack Block and he later ran a pub in North London. Ellis Jackson stayed in England and lived to be nearly 100 - he could still tap dance well into his 90s."
I am amazed at the power of collective research. The question of who was "Snowball" began with an ad found by Steve Z for the appearance of Jack Pettis and His Pets at Bach's in Philadelphia. The ad had a mention of "Snowball" of fame with Whiteman. Steve discovered the name of "Snowball" and from then on it was easy to track him down. And now, thanks to Nick we can even see what "Snowball" looked like.
Albert